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Office of the Deputy Director of Public Instruction, Bangalore rural district, , Science Study Package 2021-22, , Physics : Electricity, 1. What is a charge? What is the SI unit of charge?, Charge is a fundamental particle in an atom. It may be positive or negative., S. I. unit of charge is Coulomb (C), 2. What is the value of one coulomb?, 1 Coulomb charge = Charge present on approx. 6 × 1018 electrons, 3. What is potential difference? Write its unit?, Potential Difference (V) : Work done to move a unit charge from one point to another., S. I. unit of Potential difference is Volt (V), Potential difference (V) between two points = Work done (W)/Charge (Q), V = W/Q, The SI unit of electric potential difference is volt (V),, 4. What is the meaning of one volt?, 1 Volt : When 1 joule work is done in carrying one Coulomb charge then potential, difference is called 1 volt., Therefore, 1 volt =1 joule/1 coulomb, 1 V = 1 J C–1, Voltmeter : Instrument to measure potential difference., • It has high resistance and always connected in parallel. Symbol is, • Cell is the simplest device to maintain potential difference., • Current always flow from higher potential to lower potential., 5. How much energy is given to each coulomb of charge passing through a 6 V battery, Potential difference = Work Done/Charge, ∴ Work done = Potential difference × charge, Where, Charge = 1 C and Potential difference = 6 V, ∴ Work done = 6×1 = 6 Joule., 6. What is electric current? Write is SI unit., Electric current is the rate of flow of electric charges. motion of electrons in an electric, circuit constitutes an electric current., The electric current is expressed by a unit called ampere (A),, 7. Define on ampere., One ampere is constituted by the flow of one coulomb of charge per second, that is, 1, A = 1 C/1 s. Small quantities of current are expressed in milliampere, (1 mA = 10–3 A) or in microampere (1 μA = 10–6 A)., An instrument called ammeter measures electric current in a circuit. It is always, connected in series in a circuit through which the current is to be measured., 8. What is electric circuit and circuit diagram?, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 1

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An electrical circuit is the complete loop through which an electrical current flows. It is, made up of a series of electrical components and conductors, (e.g., batteries, electrical wires, light bulbs, etc.), The current only flows in an electrical circuit when the path is completely closed,, forming a loop., Schematic representation of electric circuit is called circuit diagram., 9. State Ohm’s Law ., Ohm’s Law : Potential difference across the two points of a metallic conductor is, directly proportional to current passing through the circuit provided that temperature, remains constant., • Mathematical expression for Ohm’s law, V∝I, V = IR, Here R is proportionality constant called resistance, R is a constant called resistance for a given metal., 10. What is resistance? Writ its SI unit., Resistance (R) : It is the property of a conductor to resist the flow of charges through, it., • S. I. unit of resistance is Ohm (Ω), 11. Define one Ohm., • When potential difference is 1 V and current through the circuit is 1 A, then resistance, is 1 ohm., 12. What is variable resistance or Rheostat?, Variable resistance (Rheostat ) is a component used to regulate current without, changing, the source of voltage., 13. On what factors does the resistance of a conductor depends?, Factors on which the Resistance of a Conductor depends :, Resistance of a uniform metallic conductor is, (i) directly proportional to the length of conductor,, (ii) inversely proportional to the area of cross-section,, (iii)directly proportional to the temperature and, (iv) depend on nature of material., 14. What is resistivity? Write its SI unit., It is defined as the resistance offered by a cube of a material of side 1m when current, flows perpendicular to its opposite faces., • Its S.I. unit is ohm-metre (Ωm)., resistance of a uniform metallic conductor is directly, proportional to its length (l) and inversely proportional to the area of, cross-section (A)., R∝l, 1, and R ∝, A, , 𝑙, , or, R = ρ, 𝐴, where ρ (rho) is a constant of proportionality and is called the electrical resistivity of the, material of the conductor., Note:, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 2

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Resistivity does not change with change in length or area of cross-section but it, changes with change in temperature., 15. How resistivity vary from materials to materials?, The metals and alloys have very low resistivity in the range of 10–8 Ω m to 10–6 Ω m., They are good conductors of electricity. Insulators like rubber and glass have resistivity, of the order of 1012 to 1017 Ω m. Both the resistance and resistivity of a material vary, with temperature., 16. How resistivity of an alloy is different from its constituent metals?, Resistivity of an alloy is generally higher than that of its constituent metals. Alloys do, not oxidise (burn) readily at high temperatures. For this reason, they are commonly used, in electrical heating devices, like electric iron, toasters etc. Tungsten is used almost, exclusively for filaments of electric bulbs, whereas copper and aluminium are generally, used for electrical transmission lines. Resistivity does not change with change in length, or area of cross-section but it changes with change in temperature., 17. Alloys are used in electrical heating devices. Why?, • Alloys do not oxidize (burn) readily at high temperature, so they are commonly used, in electrical heating devices., • Copper and aluminium are used for electrical transmission lines as they have low, resistivity., 18. List the advantages of parallel combination over series combination., (i) In series circuit, when one component fails, the circuit is broken and none of the, component works., (ii) Different appliances have different requirement of current. This cannot be satisfied, in, series as current remains same., (iii) The total resistance in a parallel circuit is decreased., 19. Write a note on electric fuse., Electric Fuse : It is a safety device that protects our electrical appliances in case of, short, circuit or overloading., • Fuse is made up of pure tin or alloy of copper and tin., • Fuse is always connected in series with live wire., • Fuse has low melting point., • Current capacity of fuse is slightly higher than that of the appliance., 20. Define Joule’s law of heating., The law implies that heat produced in a resistor is, (i) directly proportional to the square of current for a given resistance,, (ii) directly proportional to resistance for a given current, and, (iii) directly proportional to the time for which the current flows through the, resistor., H = I2Rt, 21. list the Practical Applications of Heating Effect of Electric Current., heating effect of electric current has many useful applications. The electric laundry, iron, electric toaster, electric oven, electric kettle and electric heater are some of the, familiar devices based on Joule’s heating., The electric heating is also used to produce light. The bulbs are usually filled with, chemically inactive nitrogen and argon gases to prolong the life of filament. Most of the, power consumed by the filament appears as heat, but a small part of it is in the form of, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 3

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light radiated. Another common application of Joule’s heating is the fuse used in electric, circuits. It protects circuits and appliances by stopping the flow of any unduly high, electric current, 22. What is electric power?, Electric Power: The rate at which electric energy is consumed or dissipated in an, electric, circuit., P = VI, P = I2 R, S.I. unit of power = Watt (W), 1 Watt = 1 volt × 1 ampere, • Commercial unit of electric energy = Kilo Watt hour (kWh), 1 kWh = 3.6 × 106 J, 1 kWh = 1 unit of electric energy, 23. Convert 1 kW h to joules., 1 kW h = 1000 x 60 x 60, = 3.6 × 106 watt second, = 3.6 × 106 joule (J), 24.Why is the tungsten used almost exclusively for filament of electric lamps?, Tungsten is a strong and metal having high melting point. This will not melt in high, temperature. Because of this tungsten is used almost exclusively for filament of electric, lamps., 25. Why are the conductors of electric heating devices, such as bread- toasters and, electric irons, made of an alloy rather than a pure metal?, The resistivity of an alloy is generally higher than that of its constituent metals. Alloys do, not oxidise (burn) readily at high temperatures. Because of this reason the conductors of, electric heating devices, such as bread-toasters and electric irons made of an alloy rather, than a pure metal., 26. Why is the series arrangement not used-for domestic circuits?, In case of series connection, when one component fails, the circuit it broken and none of, the components work. But in case of parallel connection, circuit divides the current, throughout the electrical gadgets. Because of this reason series arrangement is not used for, domestic purposes., 27. How does the resistance of a wire vary with its area of cross-section?, Resistance is inversely proportional to its cross section. As area is increasing resistance is, less. Thus, resistance of wire is changing with area of cross section., 28. Why are copper and aluminium wires usually employed for electricity, transmission?, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 4

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Copper and Aluminium are good conductors of electricity and they have less resistance., Hence, they are used in electricity transmission., 29. How is a voltmeter connected in the circuit to measure the potential difference, between two points?, The voltmeter should be connected in parallel between the two points to measure the, voltage between any two points., 30. What are the advantages of connecting electrical devices in parallel with the, battery instead of connecting them in series?, The advantages of connecting electrical devices in parallel with the battery instead of, connecting them in series are:, i) there will be no division of voltage among the appliances, ii) the potential difference across the devices is equal to supply voltage, iii) it reduces the effective resistance of the circuit., , Magnetic Effects of Electric Current, Additional Questions and Answer:, 1. What are the characteristics of magnetic field lines ?, Field lines arise from North pole and end into South pole of the magnet., (ii) Field lines are closed curves., (iii)Field lines are closer in stronger magnetic field., (iv) Field lines never intersect each other as for two lines to intersect, there must be two north, directions at a point, which is not possible., (v) Direction of field lines inside a magnet is from South to North., (vi) The relative strength of magnetic field is shown by degree of closeness of field lines., 2. State right hand thumb rule., Imagine you are holding a current carrying straight conductor in your right hand such that the, thumb is pointing towards the direction of current. Then the fingers wrapped around the, conductor give the direction of magnetic field., 3. What are the factors affecting magnetic field of a circular current carrying conductor?, Magnetic field is proportional to Current passing through the conductor, Magnetic field is proportional to No. of turns in the coil, Magnetic field is additive in nature i.e., magnetic field of one loop adds up to, magnetic field of another loop. This is because the current in each circular turn has, some direction., 4. What is a solenoid?, A coil of many circular turns of insulated copper wire wrapped closely in a cylindrical form., 5. The magnetic field in a given region is uniform. Draw a diagram to represent it., The magnetic field lines inside a current-carrying long straight solenoid are uniform., 6. What is electromagnetic induction?, When a conductor is placed in a changing magnetic field, some current is induced in it. Such, current is called induced current and the phenomenon is called electromagnetic induction., 7. State Flemings right hand rule., Hold the thumb, the fore finger and the middle finger of right hand at right angles to each other., If the fore finger is in the direction of magnetic field and the thumb points in the direction of, motion of conductor, then the direction of induced current is indicated by middle finger., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 5

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8. Write the difference between AC Current and DC current., AC current:, a) Direction of the current changes every half of the cycle., B) Cannot be stored., DC current:, a) Direction of the current cannot be changed during every half of the cycle, b) Can be stored., 9. What is the potential difference between live wire and neutral wire?, The potential difference between live and neutral wire in India is 220 V., 10. List three sources of magnetic fields., Three sources of magnetic fields are as follows:, (a) Current-carrying conductors, (b) Permanent magnets, (c) Electromagnets, 11. Why does a compass needle get deflected when brought near a bar magnet?, A compass needle gets deflected when brought near a bar magnet because of the interaction of, magnetic field lines of compass with the magnetic field lines of bar magnetic., 12. . List the properties of magnetic field lines., The properties of magnetic field lines are as follows:, • Magnetic field lines do not intersect with each other., • They emerge from the North Pole and merge at the South Pole., • Inside the magnet, the direction of the field lines is from the South Pole to the North Pole., 13. Why don’t two magnetic field lines intersect each other?, If two field lines of a magnet intersect, then at the point of intersection, the compass needle, points in two different directions, which is not possible. Hence, two field lines do not intersect, each other., 14. State Fleming’s left-hand rule., Fleming’s Left hand rule states that if we arrange our thumb, forefinger and middle finger of, the left hand at right angles to each other, then the thumb points towards the direction of the, magnetic force, the forefinger points towards the direction of magnetic field and the middle, finger points towards the direction of current., 15. What is the principle of an electric motor?, The working principle of an electric motor is based on the magnetic effect of current. A, current-carrying loop experiences a force and rotates when placed in a magnetic field. The, direction of rotation of the loop is given by the Fleming’s left-hand rule., 16. What is the role of split ring in an electric motor?, The split ring in the electric motor acts as a commutator. The commutator reverses the, direction of current flowing through the coil after each half rotation of the coil. Due to this, reversal of the current, the coil continues to rotate in the same direction., 17. Explain different ways to induce current in a coil., The different ways to induce current in a coil are as follows:, (a) If a coil is moved rapidly between the two poles of a horse-shoe magnet, then an electric, current is induced in the coil., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 6

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(b) If a magnet is moved relative to a coil, then an electric current is induced in the coil., 18. State the principle of an electric generator., An electric generator works on the principle of electromagnetic induction., 19. Name some sources of direct current., Cell and DC generator., 20. Which sources produce alternating current?, Power plants and AC generator., 21. Name two safety measures commonly used in electric circuits and appliances., Two safety measures commonly used in electric circuits and appliances are as follows:, (i) Each circuit must be connected with an electric fuse. This prevents the flow of excessive, current through the circuit. When the current passing through the wire exceeds the maximum, limit of the fuse element, the fuse melts to stop the flow of current through that circuit, hence, protecting the appliances connected to the circuit., (ii) Earthing is a must to prevent electric shocks. Any leakage of current in an electric, appliance is transferred to the ground and people using the appliance do not get the shock., 22. What precaution should be taken to avoid the overloading of domestic electric circuits?, The precautions that should be taken to avoid the overloading of domestic circuits are as, follows:, (a) Too many appliances should not be connected to a single socket., (b) Too many appliances should not be used at the same time., (c) Faulty appliances should not be connected in the circuit., (d) Fuse should be connected in the circuit., 23. List two methods of producing magnetic fields., the methods of producing magnetic fields are as follows:, By using a permanent magnet, By using electromagnet, By using a current carrying straight conductor, By using different types of conductors such as solenoid and circular loop, 24. How does a solenoid behave like a magnet? Can you determine the north and south, poles of a current–carrying solenoid with the help of a bar magnet? Explain., A solenoid is a long coil of circular loops of insulated copper wire. Magnetic field lines are, produced around the solenoid when a current is allowed to flow through it. The magnetic field, produced by it is similar to the magnetic field of a bar magnet. The field lines produced in a, current-carrying solenoid is shown in the following figure., In the above figure, when the north pole of a bar magnet is brought near the end connected to, the negative terminal of the battery, the solenoid repels the bar magnet. Since like poles repel, each other, the end connected to the negative terminal of the battery behaves as the north pole, of the solenoid and the other end behaves as a south pole. Hence, one end of the solenoid, behaves as a north pole and the other end behaves as a south pole., 25. When is the force experienced by a current–carrying conductor placed in a magnetic, field largest?, , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 7

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The force experienced by a current-currying conductor is the maximum when the direction of, current is perpendicular to the direction of the magnetic field., 26. Name some devices in which electric motors are used., Some devices in which electric motors are used are as follows:, (a) Water pumps, (b) Electric fans, (c) Electric mixers, (d) Washing machines, 27. A coil of insulated copper wire is connected to a galvanometer. What will happen if a, bar magnet is (i) pushed into the coil, (ii) withdrawn from inside the coil, (iii) held, stationary inside the coil?, A current induces in a solenoid if a bar magnet is moved relative to it. This is the principle of, electromagnetic induction., (i) When a bar magnet is pushed into a coil of insulated copper wire, a current is induced, momentarily in the coil. As a result, the needle of the galvanometer deflects momentarily in a, particular direction., (ii) When the bar magnet is withdrawn from inside the coil of the insulated copper wire, a, current is again induced momentarily in the coil in the opposite direction. As a result, the, needle of the galvanometer deflects momentarily in the opposite direction., (iii) When a bar magnet is held stationary inside the coil, no current will be induced in the coil., Hence, galvanometer will show no deflection., 28. Two circular coils A and B are placed closed to each other. If the current in the coil A is, changed, will some current be induced in the coil B? Give reason., Two circular coils A and B are placed close to each other. When the current in coil A is, changed, the magnetic field associated with it also changes. As a result, the magnetic field, around coil B also changes. This change in magnetic field lines around coil B induces an, electric current in it. This is called electromagnetic induction., 29. State the rule to determine the direction of a (i) magnetic field produced around a, straight conductor-carrying current, (ii) force experienced by a current-carrying straight, conductor placed in a magnetic field which is perpendicular to it, and (iii) current, induced in a coil due to its rotation in a magnetic field., (i) Maxwell’s right hand thumb rule, (ii) Fleming’s left hand rule, (iii) Fleming’s right hand rule, 30. When does an electric short circuit occur?, If the resistance of an electric circuit becomes very low, then the current flowing through the, circuit becomes very high. This is caused by connecting too many appliances to a single socket, or connecting high power rating appliances to the light circuits. This results in a short circuit., When the insulation of live and neutral wires undergoes wear and tear and then touches each, other, the current flowing in the circuit increases abruptly. Hence, a short circuit occurs., 31. What is the function of an earth wire? Why is it necessary to earth metallic appliances?, , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 8

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The metallic body of electric appliances is connected to the earth by means of earth wire so, that any leakage of electric current is transferred to the ground. This prevents any electric, shock to the user. That is why earthing of the electrical appliances is necessary., 32. Draw the diagram of electric motor and label the parts., , 33. Draw the diagram of generator and label the parts., , 34. Draw magnetic field lines around a bar magnet., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 9

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Light Reflection and Refraction:, 1. What are spherical mirrors?, Mirrors, whose reflecting surfaces are spherical, are called spherical mirrors., 2. What is pole of the mirror?, The centre of the reflecting surface of a spherical mirror is a point called the pole., 3. What is principal axis?, The line passing through the pole and the centre of curvature of a spherical mirror is, called principal axis., 4. Define the principal focus of a concave mirror., The number of rays parallel to the principal axis are falling on a concave mirror, which meat at a point is called principal focus of the concave mirror., 5. Name a mirror that can give an erect and enlarged image of an object., Concave mirror., 6. Why do we prefer a convex mirror as a rear-view mirror in vehicles?, Because these mirrors are fitted on the sides of the vehicle, enabling the driver to, see traffic behind him/her to facilitate safe driving., 7. A ray of light traveling in air enters obliquely into water. Does the light ray, bend towards the normal or away from the normal? Why?, Light ray bend towards normal. Because when a ray of light enters from rarer, medium to denser medium, it changes its direction in the second medium., 8. State the Laws of reflection., (i) The angle of incidence is equal to the angle of reflection, and, (ii) The incident ray, the normal to the mirror at the point of incidence, 9. Write the nature of the image formed in a plane mirror., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 10

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by a plane mirror is always virtual and erect. The size of the image is equal to that of, the object. The image formed is as far behind the mirror as the object is in front of it., Further, the image is laterally inverted., 10. State the Laws of Refraction., I. The incident ray, refracted ray and normal to the interface of given two, transparent media, all lie in same plane., II. The ratio of sine of angle of incidence and sine of angle of refraction is always, constant for the light of given colour and for the pair of given media., The Second Law of Refraction is also known as Snell’s Law of Refraction., That is, Sin i/Sin r =constant, The constant is called refractive index of the second medium in relation to the, first medium., 11. The refractive index of diamond is 2.42. What is the meaning of this, statement?, It means Ratio of velocity of light in air and velocity of air in diamond is 2.42., 12. Define 1 dioptre of power of a lens., 1 dioptre is the power of lens whose focal length is 1 metre 1 D = 1 m-1, 13. Name the type of mirror used in the following situations., (a) Headlights of a car., (b) Side/rear-view mirror of a vehicle., (c) Solar furnace., Support your answer with reason., (a) Concave mirrors are used as reflectors in headlights of cars. When a bulb is, located at the focus of the concave mirror, the light rays after reflection from the, mirror travel over a large distance as a parallel beam of high intensity., (b) A convex mirror is used as a side/ rear-view mirror of a vehicle because,, A convex mirror always forms an erect, virtual, and diminished image of an object, placed anywhere in front of it., • A convex mirror has a wider field of view than a plane mirror of the same size., (c) Large concave mirrors are used to concentrate sunlight to produce heat in solar, furnaces., •, , 14. . Define 1 dioptre of power of a lens., Dioptre is the SI unit of power of lens is denoted by the letter D. One dioptre can be, defined as the power of a lens whose focal length one metre., 15. The magnification produced by a plane mirror is +1. What does this mean?, The positive [+] sign of magnification [m] indicates that the image is virtual and, erect. The magnification m = 1 indicates that the image is of the same size as the, object. Thus, the magnification of +1 produced by a plane mirror means the image, formed in a plane mirror is virtual, erect and of the same size as the object., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 11

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16. Write the nature of the image formed by a concave mirror for different positions, of the object., Position of the object Position of the image Size of the image, Nature of the image, At infinity, At the focus F, Highly diminished, point-sized, Real and inverted, Beyond C, Between F and C, Diminished, Real and inverted, At C, At C, Same size, Real and inverted, Between C and F, , Beyond C, , Enlarged, , Real and inverted, , At F, , At infinity, , Highly enlarged, , Real and inverted, , Between P and F, , Behind the mirror, , Enlarged, , Virtual and erect, , The Human Eye and colourful world, Points to remember, •, , The human eye is different from the eye of other species. The human eye is classified, as simple eye structure. There are fluids present in the eye which helps in maintaining, its structure and rigidity. The parts of the eye discussed are:, , •, , The eye is spherical in shape and has a diameter of 2.3 cm on an average. The, internal structure of the eye includes- cornea, iris, pupil, lens, ciliary muscles,, retina, nerve cells, optic nerve, and yellow spot, aqueous and vitreous humor, and, suspensory ligament., , •, , The human eye, it is the most valuable and sensitive sense organ which help us to, see the beauty and the colourful world around us. It is similar to a camera. We all, have been gifted with two eyes which gives a wider field of view., , •, , Cornea: It is the outer most transparent part. It provides most of the reflection of, light., , •, , Iris: The muscles responsible for controlling eye aperture. It is the dark muscular, diaphragm that controls the size of the pupil., , •, , Lens: It is a convex lens in the case of humans. It is composed of fibrous, jelly like, material. Provides the focused real and inverted image of the object on retina., , •, , Pupil: It is the window of the eye . It is the central aperture in iris.It regulates and, controls the amount of light entering the eye., , •, , Retina: The inner part of the eye with sensory cells., , •, , Sclera: Muscular layer of the eye., , •, , Range of vision of normal eye: 25cm to infinity., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 12

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•, , Far point for normal eye : infinity., , •, , Near point for normal eye: 25cm., , •, , Part of human eye which helps us to change focal length of eye lens: ciliary, muscle., , •, , The part of human eye where image is formed: Retina., , •, , Ability of eye lens to adjust it’s focal length : power of accommodation., , Defects of human eye, •, , There are few common eye disorders seen in all individuals and are caused by several, factors. These conditions can be improved by the corrections. The defects includes:-, , Myopia – This is also called as the short-sightedness. A person with this eye defect can, only see the nearby objects clearly compared to distant objects. This condition can be, corrected using a concave lens, Hypermetropia – This is also called as the farsightedness. A person with this eye defect, can only see the distant objects clearly compared to near objects. This condition can be, corrected using a convex lens., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 13

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Presbyopia – This is an age-related condition caused due to the weakening of ciliary, muscles, hardening of the lens, and reduced lens flexibility. A person with this defect, usually finds difficulties to focus on nearby objects unable to read or write, Cataract – This is an age-related condition caused due to the loss of transparency of the, lens by erosion of lens proteins. It usually results in blurry vision, cloudy lenses and can be, corrected by replacing the old lens with an artificial lens., ➢ The image formed by retina of human eye : Real and inverted, ➢ The change in focal length of human eye is caused due to :Ciliary muscles, ➢ The least distance of distinct vision for a young adult with normal vision is, :25cm, ➢ The persistence of vision for human eye is-1/16th of a sec, ➢ The phenomenon of light responsible for the working of human eye is, :Refraction, ➢ Which of the following colours is least scattered by fog, dust or smoke :Red, ➢ The coloured light that reflects most while passing through a prism is :. Violet, ➢ The amount of light entering the eye is controlled by :Iris, ➢ The part of the eye which refracts light entering the eye from external objects, :Cornea, ➢ The variation of focal length to form a sharp image on the retina is called -----Accommodation, ➢ In human eye image is formed :On retina, ➢ Light enters eye through a transparent membrane called :Cornea, ➢ Colored portion of eye that controls amount of light reaching retina is called:, Iris, ➢ Human eye acts like a : Camera, ➢ The passage through which tears pass is : Tear gland, ➢ Thing that shuts automatically to protect eyes is known as :Eyelid, ➢ Ability of combination of dual vision of eyes is called :Binocular vision, ➢ Sunlight is a mixture of:7 visible colours, , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 14

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➢ Who discovered the experiments with glass prism that white light consists of, seven colours :Newton, ➢ The light that refracts most while passing through a prism: Violet, ➢ Which of the following colour is the least deviated on passing through a prism, :Red, ➢ The image on the retina remains for 1/16th of sec. This is called as: Persistence, of vision, ➢ The eye lens contains a liquid called : Aqueous humour, ➢ The power of lens being +4 D, suggests that it is : Convex lens, ➢ When a ray passes through a prism : It bends towards the base, ➢ The angle at which the ray gets deviated is called : Angle of deviation, ➢ At a particular minimum angle of deviation, the prism is under :Minimum, deviation position, ➢ A transparent refracting material which is bounded by two plane refracting, surfaces is :Prism, ➢ The ratio of real depth to apparent depth is called :Refractive index, ➢ The image formed by retina of human eye is :. temporary, o The property related to the sense of continuity of vision is called :., Persistence of vision, ➢ When the muscles are relaxed, the eye lens is _ Thick and the distant objects, can be seen clearly., o When looking at nearby objects the muscles Compresses the eye lens so, as to decreases its focal length., ➢ Having two eyes facilities :, i. Increasing the field view, o ii. Three dimensional view, iii. concept of distance, 1. Why does the Sun appear reddish early in the morning?, Answer – In the early morning, the sun is situated near the horizon. Light from the Sun, passes through thicker layers of air and cover larger distance before reaching our eyes., Therefore, blue light scattered the most and red light least. is why the sun appears reddish, early in the morning., 2. Why does the sky appear dark instead of blue to an astronaut?, Answer – Sky appears dark instead of blue to an astronaut because there is no atmosphere, containing air in the outer space to scatter sunlight. As there is no scattered light to reach, our eyes in outer space, so the sky appears dark., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 15

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3. Why does the Sun appear white at noon?, Answer – The light is least scattered at noon, 4. When a monochromic light having only one wavelength, passes through a prism,, will it show dispersion?, Answer – No, it will not show dispersion. It will only show deviation, 5. The sun can be seen about two minutes before actual sunrise and two minutes, after actual sunset. Why?, Answer – The sun can be seen about two minutes before actual sunrise and two minutes, after actual sunset because of atmospheric refraction., 6. Name the component of white light that deviates the least and the component that, deviates the most while passing through a glass prism., Answer – Least deviated component: Red, Most deviated component: Blue, 7. Why there is no dispersion of light refracted through a rectangular glass slab?, Answer – After refraction at two parallel faces of a glass slab, a ray of light emerges in a, direction parallel to the direction of incidence of white light. As rays of all colours emerge, in same direction, i.e., the direction of the incidence of white light, there is no dispersion., However, there is a lateral displacement., 8. Is the position of a star as seen by us in its true position? Justify your answer., Answer – No, light from stars undergoes atmospheric refraction which occurs in medium, of gradually changing refractive index. So, we see the apparent position of the star after, refraction by atmosphere., 9. Twinkling of stars is due to atmospheric, Answer – refraction of light by different layers of varying refractive indices, 10. The danger signals installed at the top of tall buildings are red in colour. These, can be easily seen from a distance because among all other colours, the red light, Answer – is scattered the least by smoke or fog, 11. When light rays enter the eye, most of the refraction occurs at, Answer –outer surface of the cornea, 12. Why is red colour light used in trains during fog?, Answer – It has high wavelength and least scattered, 13. The angle of incidence i and refraction r are equal in a transparent slab when the, value of i is, Answer - 0° ,When the incident ray falls normally on the glass slab, it will refracted, without deviation, i.e. along the normal in the glass slab. So, ∠i = ∠r, 14. What is Meant by least distance of distinct vision ofnormal human eye?, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 16

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The minimum distance at which objects can be seen most distinctly without strain is, called the least distance of distinct vision. Near point far point., 15. Explain how retina sends images to the brain and how brain helps in preparing a, sense of vision, Answer - the eye lens forms an inverted real image of the object on the retina the retina is, a delicate membrane having enormous number of light sensitive cells the light sensitive, cells get activated upon illumination and generate electrical signals these signals and, processes the information .so ,that we perceive object., 16. Explain power of accommodation. Explain in brief the near and the far point of, an eye and give their values ., Answer - Power of accommodation: it is the ability of the eye lens to adjust it’s focal, length .so , that we can see object clearly. Near point : the nearest point upto which an eye, can see the object clearly without strain is called the nearest point . The near point of, normal human eye is at a distance of 25 cm., 17. A person cannot see object beyond 1.2 m distinctly. Giving reason name the defect, of vision and name the nature of corrective lens ?, Answer - The person who cannot see object beyond 1.2 m from eye is suffering from, myopia . In myopic eye , the image of a distance object is formed in front of the retina and, not at the retina itself . This defect of vision is corrected by using a concave lens of proper, focal length., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 17

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Sources of Energy, 1. What is a good source of energy?, A good source of energy should be economical, easily accessible, easy to store and, transport and finally should do large amount of work per unit volume or mass., 2. What is a good fuel?, A good fuel is a fuel which produces large amount of heat energy when burnt,, easily available with low ignitions temperature, controllable combustion rate and, should be eco-friendly., 3. If you could use any source of energy for heating your food, which one would, you use and why?, Natural gas is used for cooking because it fulfils many of the characteristics of a, good fuel like it is highly inflammable, easily available, easy to store and transport, and it don’t produce large amount of smoke when burnt., 4. What are the disadvantages of fossil fuels?, the disadvantages of fossil fuels are:, Burning fossil fuels produces the oxides of carbon, nitrogen and sulphur that leads, to acid rain which affects our water and soil resources., Burning of coal and petroleum release of huge amount of pollutants leads to air, pollution, Burning of fossil fuels causes smog leads to breathing problems and other hazards, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 18

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Burning of fossil fuels realises carbon dioxide which causes greenhouse effect, leads to global warming., 5. Why are we looking at alternate sources of energy?, Fossil fuels takes millions of years to form and they are not available in large, quantities and cannot be replenished. Fossil fuels will get exhausted if their, consumption is not controlled. Therefore, it is better to look at alternate source of, energy like wind energy, solar energy etc., 6. What kind of mirror – concave, convex or plain would be best suited for use, in a solar cooker? Why?, For a solar cooker the heat source is sunlight for heating and cooking. The reason, why a mirror is used is to reflect and focus the sunlight. A plane mirror is used, because it reflects all the light falling on it to the desired place., 7. What is geothermal energy?, The interior regions of the earth’s crust are very hot. The temperature is so high, that even rocks can melt. If this heat is utilised as a source of energy it is called, geothermal energy., 8. What are the advantages of nuclear energy?, The advantages of nuclear energy are:, It is used to generate electricity, It is used treat diseases like cancer, The fuel once filled can be used for a long time., Large amount of energy can be obtained from nuclear fission, Fission of 1 atom of uranium produces 10 million times the energy that is obtained, by burning 1 atom of carbon, 9. Can any source of energy be pollution-free? Why or why not?, No source of energy can be completely pollution-free. Because even it is clean, its, assembly could have caused some environmental damage like production of solar, cell may cause environmental damage, the waste produced during fission are, hazardous., 10.Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel, than CNG? Why or why not?, , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 19

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Yes, Hydrogen is cleaner than CNG. Because hydrogen does not give carbon, monoxide / carbon dioxide as a pollutant and an incomplete combustion will not, takes place in hydrogen., 11.Compare and contrast fossil fuels and the sun as direct sources of energy., Fossil fuels and sun (solar energy) both are direct source of energy but they are, different., Fossil fuels, , Solar energy, , They are non-renewable resources, of energy, , They are renewable resources of, energy, , They cannot be replenished, , They can be replenished, , They cause lot of air pollution, , They are pollution free, , They are obtained from Earth's crust, as they are remaining of Dead plants, and animals, , They are obtained from sun, , 12.Compare and contrast bio-mass and hydroelectricity as sources of energy., Both bio-mass and hydroelectricity are renewable sources of energies., Biomass as a source of energy:, It is Renewable source of energy. It is a clean source of energy but rate of, availability is moderate. It is obtained from dead plants and animals., Hydroelectricity as source of energy:, It is renewable source of energy. It is a clean source of energy can be produced on, large scale but can be tampered as Limited sites causes a lot of environment, damage. It is obtained from the potential energy of the stored water., 13.What are the qualities of an ideal source of energy?, The qualities of an ideal source of energy are, It should give an adequate amount of net energy, It should be easy to store and transport, It should be convenient to use so as to give energy at a steady rate, It should be eco friendly, It should be pollution free, It should be easily accessible, 14.What are the advantages and disadvantages of using a solar cooker? Are, there places where solar cookers would have limited utility?, Advantages of solar cooker:, It provides cost free, pollution free heating device., It is a renewable source of energy, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 20

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It is inexhaustible source of energy, It is clean source of energy., Disadvantages of solar cooker:, The efficiency of solar cooker is very low, It takes much time to attend the temperature of 1000 C to 1400 C on sunny day, Solar cookers do not work on a cloudy day, 15.What are the environmental consequences of the increasing demand for, energy? What steps would you suggest to reduce energy consumption?, Industrialization demands for more energy and to fulfil these demands fossil fuels, are extracted more which disturbs the environment. Too much exploitation of fossil, fuels has an impact on the environment which led to greenhouse effect resulting in, global warming., Development and consumption of energy would go together, therefore we should, concentrate more on finding better possible steps to reduce energy consumption by, reducing unnecessary usage and using alternative source of energy. When looking, for alternative sources of energy, the following points should be kept in mind ease, and cost of extracting energy from the source, efficiency of available technology,, environmental impact of using that source., 16.How is biogas is produced from biomass?, The biogas plant has a dome-like structure built with bricks. A slurry of cow-dung, and water is made in the mixing tank from where it is fed into the digester. The, digester is a sealed chamber in which there is no oxygen. anaerobic microorganisms that do not require oxygen decompose or break down complex, compounds of the cow-dung slurry. It takes a few days for the decomposition, process to be complete and generate gases like methane, carbon dioxide, hydrogen, and hydrogen sulphide. The bio-gas is stored in the gas tank above the digester, from which they are drawn through pipes for use., 17.Bio gas is an excellent fuel. Justify the statement by giving two reasons., It burns without smoke and leave no residue therefore causes no atmospheric, pollution., (ii)Its heating capacity is high, i.e. it has high calorific value., , Chemistry:, Chemical Reaction and Equation, 1. What is balanced chemical equation?, When the number of atoms of different elements on reactant side and product side are equal,, such chemical equation is called a balanced chemical equation., 2., , Why should a magnesium ribbon be cleaned before burning in air?, , To remove oxide layer on the magnesium ribbon., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 21

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3., , Why is respiration considered as an exothermic reaction? Explain., The glucose formed is slowly oxidized to carbon dioxide and water with the release of, heat energy., , 4., , What is Precipitation Reaction?, Any reaction that produces a precipitate can be called as Precipitation reaction., , 5. I am a process which is used to prevent rusting of iron objects / articles., The rusting of iron can be prevented by painting, oiling, greasing, galvanising, chrome plating,, anodising or making alloys., 6. What is chemical combination reaction? Give example, A reaction in which two or more reactants combine to form a single product is called chemical, combination, C(s) + O2(g) → CO2 (g), 2H2(g) + O2 → 2H2 O(l), 7. What is chemical decomposition reaction? Give example., A reaction in which a single reactant breaks down to form two or more products is known as, chemical decomposition reaction, 2FeSO4 (s) → Fe2O3 (S) + SO2(g) + SO3(g) ,, CaCO3(s) → CaO (s) + CO2(g), 8. Explain the following with example. a) Thermal decomposition b) Photo chemical, decomposition c) Electrolytic decomposition, , a) Thermal decomposition : When a decomposition reaction is carried out by heating, it is called, thermal decomposition., Example:1, 2FeSO4(s), →Heat → Fe2O3(s) + SO2(g) + SO3(g), (Ferrous sulphate), (Ferric oxide), b) Photo chemical decomposition :, When a decomposition reaction is carried out by absorption of light is called Photo chemical, decomposition., Examples: white silver chloride turns grey in sunlight. This is due to the decomposition, of, silver chloride into silver and chlorine by ight., 2AgCl(s) → Sunlight→ 2Ag(s) + Cl2(g), 2AgBr(s) → Sunlight→ 2Ag(s) + Br2(g), The above reactions are used in black and white photography., c) Electrolytic decomposition, Electrolytic decomposition take place when the electric current is passed through the, compound in molten or aqueous solution., Example:, 2 H₂O → 2H₂ (g) + O₂ (g), 9. Differentiate between endothermic and exothermic reaction., Exothermic reaction. Reaction in which heat is released along with the products., CaO(s) + H2O(l), Ca(OH)2(aq) + Heat, Endothermic Reaction in which energy is absorbed, CaCO3(s) Heat, CaO(s) + CO2(g), 10. What is displacement reaction? Give example., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 22

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When a more reactive element displaces less reactive element from its compound is called, displacement reaction, Mg + 2HCl, 2MgCl2 + H2, 11. What is double displacement reaction? Give example., Double displacement reaction Reactions in which there is an exchange of ions between the, reactants, Ex ,BaCl2 + Na2SO4, 2NaCl + BaSO4, 12. Differentiate between oxidation and reduction., Oxidation :Gain of oxygen 2. loss of hydrogen, 2Cu + O2, 2CuO, Reduction :Loss of oxygen 2.gain of hydrogen, CuO + H2, Cu + H2O, 13. What are precipitation reactions? Explain with suitable example., The chemical reactions which involves the formation of insoluble solid are called precipitation, reaction., Na2SO4(aq) + BaCl2(aq), BaSO4(s) + 2NaCl(aq), 14. What are redox reactions? Give 2 examples, The reactions in which oxidation and reduction takes place simultaneously are called redox, reactions., Example (i) CuO + H2, Cu + H2O, CuO reduced to – Cu., H2Oxidised to - H2O, ii) ZnO + C → Zn + CO, C is oxidized to CO ------oxidation ZnO is reduced to Zn –reduction, 15. We need to balance a skeletal chemical equation.” Give reason to justify the statement., Skeletal chemical equation is unbalanced. We need to balance chemical equation because of law, of conservation of mass. It states that ‘matter can neither be created nor be destroyed’. Therefore,, chemical equation must be balanced in each and every chemical reaction., 16. What is Corrosion? Write preventive methods of corrosion., When a metal is attacked by substances around it such as moisture, acids, etc., it is said to, corrode and this process is called corrosion., Ex: -Corrosion (rusting) of iron: Fe2O3. xH2O (Hydrated iron oxide) Rust is a, reddish brown powder on surface of iron., 17. Marble statues often slowly get corroded when kept in open for a long time. Assign a, suitable explanation., Taj Mahal is an example of corrosion of marble. The discoloration of its marble is due to, corrosion. Air primarily consists of various pollutant gases like carbon dioxide, nitrogen dioxide,, Sulphur dioxide etc which mix with moisture in air to form acids such as carbonic acid, nitric, acid and sulphuric acid. This acid comes down as acid rain and causes corrosion of marble, statues and monuments. Marble which is composed of calcium carbonate reacts with the, different acids., 18. What is Rancidity? How can it have controlled?, The process of slow oxidation of oil and fat present in the food materials resulting in the change, of smell and taste in them is called rancidity., - By keeping food materials in air tight container., - Refrigeration of cooked food at low temperature., - By adding anti-oxidants., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 23

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19. A grey colored metal Z (Atomic weight=65) is used in making dry cell. It reacts with, dil. HCl to liberate a gas. What is the gas evolved?, The metal is Zinc. It liberates hydrogen gas on reaction with HCl., The reaction is as follows: Zn+ 2HCl → ZnCl2 + H2, 20. A magnesium ribbon is burnt in oxygen to give a white compound X accompanied by, emission of light., (i) Write the balanced chemical equation for a reaction and chemical formulae of X., (ii)Write a balanced chemical equation, when X is dissolved in water?, (i) 2Mg + O₂ ---> 2MgO, Compound X ==>MgO [ Magnesium Oxide ], (ii) if "X" , that is , Magnesium Oxide is dissolved in water , the product is Magnesium, Hydroxide, MgO + H₂O --->Mg(OH)₂, 21. Why are decomposition reactions called opposite of combination reactions? Write, equations for these reactions., In a combination reaction two or more substances are combined to form new substance while in, the decomposition reaction one substance decomposes into two or more substances. Hence, the, decomposition reactions are called opposite of combination reactions., CaCO3 (s) ⇨CaO (s) + CO2 (g) Decomposition reaction, H2 (g) + Cl2⇨ 2HCl (g) Combination reaction., 22. Draw a neat labeled diagram of “ Electrolysis of Water”., , Acid, Bases and Salts, 1. Give examples for acids, Hydrochloric acid (HCl), Sulphuric acid (H2SO4), nitric acid (HNO3), 2. Give examples for bases, Sodium hydroxide (NaOH), calcium hydroxide [Ca(OH)2],potassium hydroxide (KOH), and, ammonium hydroxide (NH4OH)., 3., , What are alkalis?, , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 24

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Water soluble bases are called alkalis. Eg:NaOH, KOH, Ca(OH)2, 4. What is a salt?, The substance produced by the neutralization reaction between acid and base is called salt., Eg: NaCl, KCl, 5. What are Indicators?, These are the substances which change their colour or odour in different types of substances., 6. Name the sodium compound used to convert hard water to soft water. Write the, formula., Washing soda- Na2CO3.10 H2O, 7. What is Chlor-alkali process?, When electricity is passed through an aqueous solution of sodium chloride (called brain), it, decomposes to form sodium hydroxide. This process is called chlor-alkali process.( because of, the products formed)., 8. What is Baking Powder?, Baking powder is a mixture of sodium hydrogen carbonate and tartaric acid. On heating it, liberates CO2 which makes the cake soft and spongy., 9. Define water of crystallization?, Water of crystallization is the fixed number of water molecules present in one formula unit of a, salt. Eg: Cu SO4.5H2O., 10. What happens to H+ / OH - on dilution?, Mixing an acid or base with water results in decrease in the concentration of ions (H3O+ /OH–), per unit volume. Such a process is called dilution., , 11. Write the differences between acids and bases, ACIDS, BASES, 1.Sour taste, 1. Bitter taste, 2. Acid + Blue litmus -----Red (ABR), 2. Base + Red litmus------- Blue(BRB), +, 3. Have more H ions, 3.Have more OH—ions, 4. PH is less than 7, 4. PH is above seven and below 14, 12. What is neutralization reaction? Give example., The reaction between an acid and base to form salt and water is called neutralization reaction., Acid, + Base, → Salt, + Water, HCl(aq) + NaOH(aq) → NaCI(aq )+, H2O(l), 13. How does zinc react with H2SO4? Write the equation., dil. acids react with metals to produce salt and release Hydrogen gas., Ex: Zn + H2SO4 → ZnSO4 + H2, 14. What is pH Scale? Explain., The strength of an acid or base is measured on a scale of numbers called the pH scale., • pH is a scale for measuring H+ ion concentration in a solution ., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 25

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•, •, •, , p in pH stands for ‘potenz’ a German word which means power., The pH of a solution is inversely proportional to the concentration of hydrogen ions in it., The pH scale has values from 0 to 14. According to the rules of ph scale, pH = 7 → neutral solution, pH less than 7 → acidic solution, pH more than 7 → basic solution, , 15. Name the gas produced when acids react with metals? How will you test it?, Hydrogen gas is produced when metals react with then we pass the hydrogen gas through soap, solution it produces bubbles. if you take a candle near the purple it explodes with pop sound., 16. Which gas is produced when metal carbonates react with acids and how can you, confirm the gas?, Carbon dioxide is released. When we pass carbon di oxide through lime water, it turns milky., 17. Two solutions' A 'and 'B' having pH 6 And 8 respectively. Which of them have more, hydrogen ions? Which one is acid and which one is base among them., Solution 'A' has more hydrogen ions. Solution 'A 'is acidic and solution' B' is basic. Because if, the solution has pH more than 7 it will be base and pH less than 7 it will be acid., 18. What is acid rain? What are its effects?, If the pH of rain water decreases below 5.6 it is called acid rain. If this water mixes with, rainwater it affects the survival of aquatic life., 19. Write the Preparations and uses of following salts., Salt Names, Common Salt NaCl, Chemical name:, Sodium Chloride, Common name:, Common Salt, , Preparations, The salt formed by combination, of hydrochloric acid and sodium, hydroxide solution is called, sodium chloride., HCl + NaOH →NaCl + H2O, , Caustic Soda NaOH, Chemical, name:, Sodium hydroxide, Common, name:, Caustic Soda, , When electricity is passed through, an aqueous solution of sodium, chloride (called brine), it, decomposes to form sodium, hydroxide., 2NaCl(aq), +, 2H2O(l), →2NaOH(aq), +, , Cl2(g) + H2(g), Bleaching, powder, CaOCl2, Chemical name:, Calcium oxy chloride, Common name:, Bleaching powder, , DDPI Bangalore Rural Dist, , Bleaching powder is produced by, the action of chlorine on dry, slaked lime [Ca(OH)2]., Ca(OH)2 + Cl2 → CaOCl2 +, H2O, , Science Study Package 2021-22, , Uses, i) Used in Cooking, ii)Used as raw material for various, materials of daily use, such as, sodium hydroxide, baking soda,, washing soda, bleaching powder, and many more., Products Formed and Uses, At the Anode: Chlorine gas, Water disinfectant, Swimming, Pools, PVC, CFCs, Pesticides, At the cathode: Hydrogen gas., Fuels, margarine, Ammonia for, fertilisers, Near the cathode: Sodium, hydroxide., Degreasing metals, Soaps and, detergents, Paper making, Artificial, fibres, i) For bleaching cotton and linen in, the textile industry, for bleaching, wood pulp in paper factories and for, bleaching washed clothes in, laundry;, (ii) As an oxidising agent in many, chemical industries; and, iii) To make drinking water free, from germs., pg. 26

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Baking soda NaHCO3, Chemical name:, Sodium Hydrogen, carbonate, Common name: Baking, soda, , Sodium hydrogencarbonate is, produced on a large scale by, reacting a cold and concentrated, solution of sodium chloride(brine), with ammonia and carbon, dioxide., NaCl + NH3 + CO2 + H2O, → NaHCO3, + NH4Cl, , washing soda, Na2CO3.10H2O, Chemical, name:, sodium carbonate, Common, name:, washing soda, , Sodium carbonate can be obtained, by, heating, baking, soda., Recrystallisation, of, sodium, carbonate gives washing sodasodium carbonate, it is a basic salt., Na2CO3, + 10H2O, →, Na2CO3.10H2O, , POP(Plaster Of, Paris) CaSO4.1/2H2O, Chemical, name:, calcium sulphate Hemi, hydrate., Common name:, POP(Plaster Of Paris), , On heating gypsum at 373 K, it, loses water molecules and, becomes, calcium, sulphate, hemihydrate., CaSO4.2H2O, →Heat→, CaSO4.1/2H2O, , (i) For making baking powder,, which is a mixture of baking soda, and a mild edible acid such as, tartaric acid., (iI) Commonly used in the kitchen, for making tasty crispy pakoda, etc., 2NaHCO3 →Heat→ Na2CO3 +, H2O + CO2, (iii) Sodium hydrogen carbonate is, also an ingredient in antacids. Being, alkaline, it neutralises excess acid in, the stomach and provides relief., (iv) It is also used in soda-acid fire, extinguishers., (i) Sodium carbonate (washing, soda) is used in glass, soap and, paper industries., (ii) It is used in the manufacture of, sodium compounds such as borax., (iii) Sodium carbonate can be used, as a cleaning agent for domestic, purposes., (iv) It is used for removing, permanent hardness of water, i) used for making toys, materials, for decoration and for making, surfaces smooth., ii)for making casts in dentistry., iii) Doctors use as plaster for, supporting fractured bones in the, right position., iv)as a fire-proofing materials., v)in chemistry laboratories for, sealing air gaps in apparatus., , 20. Give scientific reasons for the following questions:, a. Why do not acids show acidic behavior in the absence of water?, Ions are produced only in aqueous medium and presence of H+ ions are responsible for the, existence of acidic properties., b. Plaster of Paris should be stored in moisture proof containers. Explain why?, Plaster of Paris (POP) is chemically calcium sulphate hemihydrates (CaSO4. 1/2 H2O). When it, comes in contact with water it sets into hard solid mass, called gypsum., c. Why milk and sours food substances are not stored in copper and brass container?, Because, milk and sours food reacts with brass and copper release hydrogen gas and some toxic, substances., d. Why does dry HCl gas not change the colour of dry litmus paper?, , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 27

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Dry HCl gas does not contain any H+ or produces H3O+ ions, so it does not show any acidic, property. Hence, it does not change the colour of dry litmus paper. To show its acidic behavior, it, needs water., e. Solutions of glucose and alcohol do not exhibit acidic property. Give scientific reason., Why?, Solutions of glucose and alcohol do not exhibit acidic property because they don’t produce, Hydronium ions., f., , Acid solution conducts electricity why?, It produces hydronium ions in solution state. So, it conducts electricity., , g. While diluting an acid, why is it recommended that the acid should be added to water, and not water to the acid?, Dilution of a concentrated acid is a highly exothermic reaction and a lot of heat is generated. The, acid must always be added slowly to water with constant stirring. Water is added to the, concentrated acid, the heat generated may cause the mixture to splash out and cause burns. The, glass container may also break due to excessive local heating., h. Why Metallic Oxides are called Basic Oxides?, Metallic oxides react with acids to give salts and water, similar to the reaction of a base with an, acid, hence metallic oxides are said to be basic oxides., i. Why Non-Metallic Oxides are called Acidic Oxides?, Non-Metallic oxides react with bases to give salts and water, similar to the reaction of an acid, with a base, hence metallic oxides are said to be basic oxides., , j. Why do people use antacids during indigestion?, During indigestion stomach produces more acid. This causes pain or irritation in the stomach., By taking antacids like magnesium hydroxide or baking soda the acid neutralizes and reduces, pain., k. Why do dentists suggest basic toothpaste?, Bacteria in our mouth produce acids. It causes tooth decay. By using basic toothpaste, we can, neutralize the acid and reduce tooth decay., l. what is the reason for the acidity of soil and how can we correct it?, Acidity of the soil is due to acid rain. It can be controlled by adding chalk powder or organic, compounds or quick lime to the soil., 21. Describe the uses of PH in our Daily life?, a) Plant and animal’s pH sensitive: ACID RAIN: When pH of rain water is less than 5.6, it, is called acid rain. When acid rain flows into the rivers, it lowers the pH of the river water., The survival of aquatic life in such rivers becomes difficult., b) pH of the soil: Plants require a specific pH range for their healthy growth., c) Tooth enamel is corroded when the pH in the mouth is below 5.5. Using toothpastes,, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 28

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which are generally basic, for cleaning the teeth can neutralize the excess acid and, prevent tooth decay., d) Self-defense by animals and plants: Bee-sting leaves an acid which causes pain and, irritation. Use of a mild base like baking soda on the stung area gives relief., e) Self defence by animals and plants: Bee-sting leaves an acid which causes pain and irritation., Use of a mild base like baking soda on the stung area gives relief. Stinging hair of nettle, leaves, inject methanoic acid causing burning pain., , 22. Draw the neat labeled diagram to show the acid solution in water conducts electricity., , 23. Draw the neat labeled diagram to show or identify that all the compounds having, hydrogen are not acids, , Metals and Non-metals, 1) Give an example of metal which, a) Liquid at room temperature – Mercury c) can be easily cut with knife - Sodium, b) Best conductor of heat - Silver, d) poor conductor of heat - Mercury and, lead, 2) Define, , a)Malleability Ans: The ability of metals to be made in to thin sheets., b) Ductility Ans: The ability of metals to be drawn in to thin wires., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 29

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c) Sonority, , Ans: The metals that produce a sound on striking a hard surface., , 3) Give reasons a) Platinum, gold and silver are used to make jewels., Ans : Because they are very lustrous, very less reactive and do not corrode easily., 4) Differentiate between metals and non-metals on their physical properties, METALS, NON METALS, Lustrous, Non lustrous, Hard, Brittle, Malleable, Non malleable, Ductile, Non ductile, Good conductor of heat and electricity, Bad conductor of heat and electricity, Sonorous, Non sonorous, High melting point and boiling point, Low melting point and boiling point, 5) Differentiate between metals and non-metals based on their chemical properties?, METALS, NON METALS, Metals are electropositive., Non-metals are electronegative., They react with oxygen to form basic oxides., They react with oxygen to form acidic or neutral, oxides., These have ionic bonds., These have covalent bonds., They react with water to form oxides and, They do not react with water., hydroxides. Some metals react with cold water,, some with hot water, and some with steam., They react with dilute acids to form a salt and, evolve hydrogen gas. However, Cu, Ag, Au, Pt, Hg, do not react., , They do not react with dilute acids. These are, not capable of replacing hydrogen., , They react with the salt solution of metals., Depending on their reactivity, displacement, reaction can occur., , These react with the salt solution of non-metals., , They act as reducing agents (as they can easily lose, electrons)., , These act as oxidising agents (as they can gain, electrons)., , 6) What are amphoteric oxides? Give two examples of them., Ans: Metal oxides which react with both acids as well as bases to produce salts and water are, known, as amphoteric oxides. Ex: Aluminum oxide, zinc oxide etc., 7) Give reasons, a) Sodium, potassium and lithium are kept in kerosene oil., b) Aluminium is highly reactive metal, yet it is used to make utensils for cooking., c) Tarnished copper vessels are cleaned with lemon or tamarind juice., Ans: a) Sodium, potassium, and lithium are very reactive metals and react very vigorously, with air as well as water. Therefore, they are kept immersed in kerosene oil in order to prevent, their contact with air and moisture., b) Though aluminium is a highly reactive metal, it is resistant to corrosion. Also, it is light in, weight and a good conductor of heat. Hence, it is used to make cooking utensils., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 30

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c) Copper reacts with moist carbon dioxide in air to form copper carbonate and as a result,, copper vessel loses its shiny brown surface forming a green layer of copper carbonate. The citric, acid present in the lemon or tamarind neutralises the basis copper carbonate and dissolves the, layer., 8) Zinc liberates hydrogen gas when reacted with dilute hydrochloric acid, whereas copper, does, not. Why?, Ans: Zinc is more reactive than hydrogen. But copper is less reactive than hydrogen., 9) A shiny brown metal X, on heating in air becomes black in colour. Name the metal X, and the black coloured compound formed., Ans: The metal ‘X’ is copper and the black coloured compound formed is copper oxide., 10) Magnesium floats on water when it reacts with hot water. Give reason., Ans: Magnesium starts floating because the bubbles of hydrogen gas formed stick to the, surface of the metal., 11) Why aluminium Oxide is referred as amphoteric oxide?, Ans: Aluminium Oxide reacts with both acid as well as bases to produce salts and water., 12) Food cans are coated with Tin and not Zinc because, a) Zinc is costlierthanTin, c) zinc is more reactive thanTin, b) Zinc has a higher melting pointthanTin, d) zinc is less reactive thantin, Ans: Food cans are coated with tin and not with zinc because zinc is more reactive than tin., 13) What is reactivity series? Write the reactivity series., Ans: K  Na  Ca  Mg  Al  Zn  Fe  Pb  Cu  Ag  Au, 14) Why do ionic compounds have high melting points?, Ans: Ionic compounds have strong electrostatic forces of attraction between the ions., Therefore, it requires a lot of energy to overcome these forces. That is why ionic compounds, have high melting points., 15) Describe the formation of ionic bond in the sodium chloride., Ans: A sodium atom has one electron in its outermost shell. If it loses the electron from its, M shell then its L shell now becomes the outermost shell and that has a stable octet. The nucleus, of this atom still has 11 protons but the number of electrons has become 10, so there is a net, positive charge giving us a sodium cation Na+. On the other hand chlorine has seven electrons in, its outermost shell and it requires one more electron to complete its octet. If sodium and chlorine, were to react, the electron lost by sodium could be taken up by chlorine. After gaining an, electron, the chlorine atom gets a unit negative charge, because its nucleus has 17 protons and, there are 18 electrons in its K, L and M shells. This gives us a chloride anion C1–. So both these, elements can have a give-and-take relation between them as follows Sodium and chloride ions,, being oppositely charged, attract each other and are held by strong electrostatic forces of, attraction to exist as sodium chloride (NaCl)., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 31

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16) Mention the characteristics of ionic compounds, Ans: * They are solids, brittle and break in to pieces when pressure is applied., They have high melting and boiling points. * They are soluble in water but insoluble in, organic solvents. * They conduct electricity in molten state. They have ionic bond., 17) Common salt conducts electricity only in molten state. Why?, Ans: Because common salt contains ions in molten state., 18) Name two metals which are found in nature in the free state? Ans: Platinum and gold., 19) Give reasons, a) Carbonate & sulphide ores are usually converted into oxides during the process of, extraction., Ans: Carbonate and sulphide ores are usually converted into oxides during the process of, extraction because metals can be easily extracted from their oxides rather than from their, carbonates and sulphides., 20) Differentiate between roasting and calcinations?, Roasting, Calcinations, The sulphide ores are converted in to oxides by, The carbonate ores are changed in to oxides, heating strongly in the presence of excess air., by heating strongly in limited air., 21) What is thermite reaction?, Ans: Thermite reactions are highly exothermic. The amount of heat evolved is so large that the, metals are produced in the molten state. Hence used to join railway tracks or cracked machine, parts., 22) What are alloys?, Ans: An alloy is a homogeneous mixture of two or more metals or a metal and a non-metal., 23) Give reason why copper is used to make hot water tanks and not steel (an alloy of iron), Ans: Copper does not react with cold water, hot water, or steam. However, iron reacts with, steam. If the hot water tanks are made of steel (an alloy of iron), then iron would react, vigorously with the steam formed from hot water., 24) What is corrosion? List the techniques used to prevent corrosion of metals., Ans: When metals are exposed to moist air for a long time acquires a coating of their respective, oxides called corrosion or rust. Corrosion can be prevented by painting, oiling, greasing,, galvanizing, chrome plating, anodizing or making alloys., 25) Define Galvanization., Galvanization is a method of protecting steel/iron from rusting by coating them with thin layer of, zinc., 26) Draw a neat labeled diagram of action of steam on metal., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 32

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27)Draw a neat diagram of Testing the conductivity of a salt solution., , 28) Draw a neat labeled diagram of Electrolytic refining of copper., , Carbon and its compounds, 1. What are hydrocarbons?, Compound containing only carbon and hydrogen are called hydrocarbons, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 33

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2. Why carbon is tetravalent?, Carbon atom has 4 electrons in the outermost shell. It needs 4 more electrons to complete, its octet. Therefore, carbon is tetravalent., 3., , Define the following, Covalent bonding, Bond formed by sharing of valence electrons, between atoms, Isomerism, Compounds have same molecular formula but, different structures. This phenomenon is called, Isomerism., , Catenation, Ability of carbon to form bonds with, other atoms of carbon to give large, molecules., Homologous series, A group of carbon compounds with CH2, difference between two successive, members., , 4., , Write the differences between saturated and unsaturated hydrocarbons, Saturated hydrocarbons, Unsaturated hydrocarbons, 1. All the carbon atoms are bounded by, 1. A double or triple bond is present in the, single bonds., hydro carbon chain, 2. They are less reactive., 2. They are more reactive., 3. They burn without smoke., 3. They burn with smoke., , 5., , Mention differences between Alkanes, Alkenes and Alkynes., Alkanes, Alkenes, Alkynes, They are saturated., They are aliphatic, They are aliphatic, unsaturated., unsaturated., Ending with “ane”, Ending with “ene”, Ending with “yne”, They have single bond ( ), They are open chain, They are open chain, between the carbon atoms., hydrocarbons with double, hydrocarbons with triple, bond (C = C), bond (C C), The general formula is, The general formula is, The general formula is, CnH2n+2, CnH2n, CnH2n-2, They are also called, They are commonly called, paraffins., olefins., 6. Draw Dot structure of Methane?, , 7., , What would be electron dot structure of carbon dioxide which has a formula CO2., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 34

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8. Draw electron dot structures for (a) Ethanoic acid (b) H2S (c) Propanone (d) F2, (e)CCl4, , e), , 9. What are functional groups? Give two examples., Functional groups are the site where reactions occur in organic molecules. They, are specific atoms (or) group of atoms within molecules that are responsible for, the characteristic chemical reactions of those molecules., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 35

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10. How can we convert unsaturated hydrocarbons into saturated hydrocarbons., , or, , What is a hydrogenation reaction? Write an equation to represent this, reaction?, Heating unsaturated hydrocarbons with hydrogen in the presence of nickel/ palladium, catalyst gives saturated hydro carbons., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 36

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Ni Catalyst, The process by which hydrogen atoms are added to unsaturated hydrocarbons in the, presence of heated and finely divided nickel so as to form saturated hydrocarbons, is called, hydrogenation., Industrially hydrogen ion is used to convert unsaturated vegetable oils to saturated vegetable, oils (commonly called vanaspati ghee) by passing hydrogen through them in the presence, of finely divided nickel., , 11. Explain the oxidation reaction of hydrocarbons with one example, Heating ethanol with 5% solution alkaline KMnO4 or acidified K2Cr2O7 Ethanoic acid, is obtained., CH3CH2OH, , ALK KMNO /ACIDIFIED K Cr O, 4, 2 2 7, , CH3COOH + H2O, , 12. Why the conversion of ethanol to ethanoic acid is is called anoxidation reaction?, When ethanol is oxidized, hydrogen is removed from its molecule and oxygen is, added so as to form ethanoic acid. Thus, conversion of ethanol into acetic acid is, anoxidation reaction, 13. What is substitution reaction? Illustrate with example?, A reaction in which one or more hydrogen atoms of an organic compound is/ are, replaced by other., CH4, + Cl2, →, CH3Cl, +, HCl, Methane Chlorine, Chloro Methane Hydrochloric acid, CH3Cl, + Cl2, →, CH2Cl2, + HCl, Dichloro methane, CH2Cl2, + Cl2, →, CHCl3, + HCl, Trichloro methane, CHCl3 + Cl2, →, CCl4, + HCl, 14. Write a note on Ethanol?, -Ethanol is good solvent so it is used in medicines such as tincture iodine, cough syrups & many, tonics., -Ethanol is soluble in water in all proportions., -long term consumption of alcohol leads to many health problems., -Ethanol is commonly called Alcohol., -Ethanol is liquid at room temperature., 15. Explain the reaction between ethanol and sodium., When Ethanol reacts with sodium, sodium ethoxide is formed and hydrogen gas is evolved., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 37

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2CH3CH2OH, → 2CH3CH2O-Na+ + H2, Ethanol, Sodium ehoxide, 16. How does we get unsaturated hydrocarbon with ethanol. Write chemical equation., Heating ethanol at443 K with excess concentrated sulphuric acid results in the dehydration of, ethanol to give ethene., Hot Conc H2SO4, CH3 –CH2- OH -------------------------→ CH2 = CH2 + H2O, 2Na +, , 17. Why acetic acid is called glacial acetic acid?, Acetic acid has very low melting point i.e. 290 K, hence it freezes during winters in cold, countries. So it is called glacial acetic acid., 18. What is vinegar?, The 5% – 10% aqueous solution of acetic acid is called vinegar., 19. Distinguish between esterification and saponification reactions of organic compounds., (a) Esterification: Reaction in which carboxylic acid reacts with alcohol in presence of conc., H2SO4 to form a fruity smelling compound called ester., CH3COOH, +, C2H5OH, → CH3COOC2H5 + H2O, Ethanoic acid, Ethanol, Ester, (b) Saponification: It is a reaction in which an ester reacts with alkali solution to form a, compound called soap., CH3COOC2H5 + NaOH, → C2H5OH, + CH3COONa, Pentanone(ester), Ethanol, sodium acetate, 20. How doe ethanoic acid reacts with base? Give example., Ethanoic acid reacts with a base sodium hydroxide to give a salt called sodium acetate and water., CH3COOH + NaOH →, CH3COONa + H2O, 21. How does ethanoic acid react with carbonates and hydrogen carbonates? Show it with, the equation., Ethanoic acid reacts with carbonates and hydro carbonates to form salt, CO2 and H2O.The salt, formed is sodium acetate., 2CH3COOH, +, Na2CO3, →, 2CH3COONa + H2O + CO2, Ethanoic acid, sodium carbonate, sodium acetate, 22. What are soaps and Detergents?, Soaps: Soaps are sodium or potassium salts of long chain of carboxylic acids., Detergents: Detergents are generally sodium salts of sulphonic acids or ammonium salts, with chlorides or bromides ions., 23. Why do we need more water to clean in hard water., Hard water as calcium and magnesium salts. They will act with soap to form scum. So we need, more soap to clean in hard water., 24. Soaps form scum with hard water. Explain why? How this problem is overcome by use, of detergents?, Scum formation: Soaps form scum with hard water because hard water has salts of calcium and, magnesium which react with soap to form insoluble compound called scum. In case of, detergents, the salts present in hard water does not react with the molecules of detergent to form, insoluble compound called scum, but the molecules of detergent remain as it is and helps in the, cleansing action., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 38

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25. Explain the mechanism of the cleansing action of soaps., A molecule of soap is made up of two parts:, (i) An ionic part which is hydrophilic, i.e., water soluble., (ii) A hydrocarbon chain which is hydrophobic, i.e., water repellent (oilsoluble)., , Long chain of hydrocarbon, polarend, (hydrophobic end), (hydrophilic end), When dirty clothes are treated with soap it forms micelles. The hydrocarbon end attaches, itself to dirt. After rinsing with water, the ionic end of the micelle attaches to water. So the dirt, with soap micelle is carried away by water., , 26. Give difference between soap and detergent., Soap, , Detergents, , -Soaps are the sodium salts of the long, chain carboxylic acids, , -Detergents are generally ammonium or, sulphonate salts of sodium with chlorides or, bromides ions., -Soaps are not suitable for washing with, -Detergents do not form insoluble scum with, hard water as it forms insoluble scum., hard water., -Soaps are prepared from fats or, -Detergents are not prepared from fats or, vegetable oils., Vegetable oils., -Biodegradable, -Non-Biodegradable, it pollutes soil and water., *** Practice all the structure of Alkanes, Alkenes, Alkynes and other hydrocarbon, compounds, , Periodic classification of elements, 1. Why did scientists try to classify the elements?, As more elements were discovered by scientists, it was difficult to organize the information and, properties of the elements. Hence scientists started finding similarities and began to group them, based on the properties., 2. State Dobereiner's law of triads., When the 3 elements were arranged in the increasing order of their atomic mass The atomic mass, of the middle ailment was roughly the average of the atomic masses of the other 2 elements., 3. State Newlands law of octaves, When the elements are arranged in the increasing order of their atomic mass every 8th element has, properties similar to that of the 1st., 4., , State Mendeleev periodic law, , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 39

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The properties of the elements are the periodic functions of their atomic mass, 5. State modern periodic law, Mobile the properties of the elements are the periodic functions of their atomic number, 6. What are valence electrons?, The electrons present in the outermost shell of the element are called valence electrons., 7. Define Valency., The combining capacity of an element is called as valency., 8. Define atomic size, The radius of an atom is called us atomic size. It is the distance between the nucleus and the, outermost shell., 9. What is effective nuclear charge?, The effective nuclear charge is the net positive charge experienced by an electron in a, polyelectronic atom., 10. Define electro negativity., The tendency of an atom to attract a shared pair of electrons (or electron density) is its electro, negativity., 11. What do you mean by electro positivity of an element?, The tendency of an element to lose electrons and become a positive iod is called as electro, positivity of an element., 12. What were the limitations of Dobereiner's classification?, Dobereiner's could find only 3 triads from the elements known at that time. Hence this system of, classification was not found to be useful., 13. Why do you think Mendeleev placed noble gases in a separate group?, Noble gases were chemically inert and hence he placed them in a separate group., 14. What suggestion of Henry Moseley led to the modification of Mendeleev’s periodic table, into modern periodic table?, Henry Moseley's Suggestion that atomic number is more fundamental property than atomic mass,, led to the modification of Mendeleev's periodic table into modern periodic table., 15. Why do atomic size and ionization energy have reciprocal relation?, Atomic size is the distance from the nucleus to the valence shell. Ionization energy is the energy, required to remove the most loosely held electron from a gaseous atom or ion. Ionization energy, increases across a period and decreases down the family. So as the atomic size increase less, ionization energy is required to remove electron., 16. Name the group having tetravalency., The group having tetravalency is 14., 17. Name the element having a monoatomic molecule?, 18th group elements, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 40

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18. ‘f’ block elements are kept separate why?, The block elements have more horizontal similarity than vertical similarity as seen in s, p and d, block elements., 19. In modern periodic table hydrogen is placed separately. Why?, Hydrogen shows properties of both the halogen group and the 1st group elements that is the reason, why it is placed separately., 20. Why do group 1 elements form unipositive ions?, The elements of the 1st group have only 1 valency, Because of this they can donate 1 electron., Hence their unipositive ions., 21. Define groups and periods, Groups: The vertical columns of the periodic table are called groups., Periods: The horizontal rows of the periodic table are called periods., 22. What are metalloids? give examples, Elements whose properties are intermediate between metals and non-metals are called, metalloids. Ex- Boron(B), Silicon (Si), Germanium (Ge), Arsenic (As),, 23. Why are noble gases placed in different group?, The outer shell of the noble gases is completely filled. Hence, they do not require any electron and, they don't participate in any chemical reaction. Therefore, they are placed in the 18th group, separately., 24. Ritu argues that Na, Si and Cl follow Dobereiner’s law of triads, whereas, Seema, says they do not follow Dobereiner’s law of triads. Who among them is correct and why?, (Atomic masses of Na-23, Si-28, Cl-35.5), A= Na-23, B= Si-28, C= Cl-35.5, According to Law of triads law, B =A+C = 23+ 35.5 = 58.5, 2, 2, 2, = 26.25, Since the answer is not near the predicted value, Seema is telling correct x, 25. What is atomic radius? How does it change along a period in the modern periodic, table?, Nuclear size / radius is the distance between the nucleus and the outermost shell of the atom., In the modern periodic table, it decreases from left to right in a period and increases down the, group., 26. X element belongs to the 13th group. Write its electronic configuration and valency?, X = 13, Electronic configuration K = 2, L = 8 M = 3, Valency - 3, 27. How does metallic property change in the periodic table when going from left to right, across a period and down the group?, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 41

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In the modern periodic table, the metallic property decreases when we move left to right in a, period. The metallic property increases when we move down the group., 28. List the limitations of Newland’s law of octaves., Limitations of Newland's octave rule were, 1. This rule did not apply after calcium., 2. The elements invented after Newland’s law did not follow the law., 3. The position of Cobalt and nickel could not be explained., 4. Iron, similar to nickel and cobalt properties, was kept away from them., 5. With the invention of inert gases the octave rule became irrelevant., 29. What are the uses of periodic table?, Uses of a modern periodic table, i. Elements are placed in increasing order of atomic number, which is the basic property of the, period., ii. Elemental trends are steadily rising., iii. In addition to describing the elemental tendencies, the relationship between the trends and the, electron configuration can be established., iv. If the properties of one element of the group is known, the properties of the other elements of, the group can be predicted., v. This table is easy to remember and study., 30. List the achievements or advantages of the Mendeleev periodic table., Achievements or advantages of a periodic table by Mendeleev are, 1. The atomic mass of the elements were taken into account to classify their basic properties and, similar chemical properties., 2. He chose properties of the elements based on oxides hydrogen and oxygen., 3.Mendeleev left a few blank boxes and predicted the availability of elements that had not been, discovered until then., 5. The properties of some of the elements that he predicted were discovered during his lifetime, and provided evidence of the usefulness of his table., 31. What were the limitations of Mendeleev's periodic table, The limitations of Mendeleev's periodic table were, 1. Hydrogen was not given fix position., 2. Discovery of Isotopes (elements with same atomic numbers but different atomic masses) could, not find a place in the table., 3 Atomic masses do not increase in regular manner, So it was difficult to predict how many, elements would be invented between the 2 elements, 32. How did modern periodic table remove various anomalies of Mendeleev's periodic, table?, 1. Hydrogen was given suitable position in the modern periodic table., 2. Many properties of the elements were described by atomic number., 3. Elements like nickel and cobalt that had property similar with iron were placed with it., 33. Write the group and the period for the following elements, a) Sodium (atomic No-11), K = 2, L = 8, M = 1, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 42

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Period-3, Group-1, b) Oxygen (atomic number 8), K = 2 and L = 6, Period-2, Group-16, 34. What do you mean by metallic character of an element? How does it vary as we go down, the group? Give reason for this variation., Metallic properties are the properties of the elements that are capable of giving up electrons., Metallic properties increase as we move down the group, because the greater the radius of the, atom, the more electrons in the outermost orbit, give away electrons with less nuclear charge., 35. In modern periodic table, use of atomic number was more beneficial. How? Explain, Only the atomic number of elements varies. Different elements may have the same atomic mass,, but the atomic number is different. For this reason, the atomic number is more appropriate., 36. Periodic table, [a] A soft metal stored under kerosene - Sodium, [b] An element which is tetravalent and forms the basis of organic chemistry - Carbon, [c] An element which is an inert with atomic number 2 - Helium, [d] The metal which is an important constituent of limestone - Calcium., , Biology: - LIFE PROCESSES, 1. Name the process that enables carbon and energy available to autotrophs., Photosynthesis, 2. Why is diffusion insufficient to meet the oxygen requirement of multicellular organisms?, In multicellular organisms all the cells of the body are not in direct contact with its surrounding to, carryout diffusion., 3. Write the equation that represents photosynthesis., , 4. Differentiate between autotrophic and heterotrophic nutrition., Autotrophic nutrition, DDPI Bangalore Rural Dist, , Heterotrophic nutrition, , Science Study Package 2021-22, , pg. 43

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1. They obtain their food by photosynthesis, , 1. They obtain their food from other plants, and animals, 5. What are the important events of photosynthesis?, 1. Absorption of light energy by chlorophyll 2.Conversion of light energy to chemical energy and, splitting of water molecules into hydrogen and oxygen. 3. Reduction of carbon dioxide to, carbohydrates., 6. Differentiate between saprophytes and parasites, Saprophytes, 1. They take food from dead and decaying, organisms, 2. They live on dead and decaying matter, 3. They breakdown food outside their body, 4. Ex – bread moulds, mushrooms, yeast, , Parasites, 1. They obtain food from other living, organisms., 2. They live in on the bodies of other, organisms, 3. They usually absorb completely digested, food from the host., 4. Ex – Cuscuta, lice, leeches, tapeworm, 7. What are stomata? How are they beneficial to plants?, Tiny pores present on lower surface of leaves are called stomata. They help in transpiration and, gaseous exchange., 8. How is opening and closing of stomata controlled?, The opening and closing of stomata is controlled by guard cells. When the plants don’t need, carbon dioxide, water flows in to guard cells. So they swell and open. Similarly the pore closes if, the guard cells shrink., 9. What is the importance of photosynthesis?, 1) The food synthesized through photosynthesis nourishes all the organisms on the Earth., 2) Photosynthesis is the main process involved in the recycling of oxygen., 3) It helps in controlling of CO2 level in the environment, 10. How does amoeba obtain its nutrition?, 1. Amoeba takes in food by cell surface 2. Food is digested in food vacuole 3. Digested food is, absorbed by cytoplasm 4. Undigested food moves to cell surface and thrown out., 11. What is peristaltic movement? What is its significance?, The rhythmic contraction of gut muscles is called peristaltic movement. It helps to push food, throughout the gut., 12. What is emulsification of fat? Where does it take place? What is its significance?, , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 44

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The process of breakdown of larger fat droplets into smaller droplets of fat with the help of bile, salts present in bile juice. It helps to increase the surface area for enzyme action. This action takes, place in small intestine., 13. Name the secretions secreted from Gastric glands., Hydrochloric acid (HCl), Pepsin, Renin, Mucous and small amount of Gastric lipase, 14. Write the functions of the following., 1. Salivary amylase (saliva) – converts starch in to sugar, 2. Hydrochloric acid (stomach) – 1. Creates acidic medium and activates pepsin 2. kills germs, 3. bile salts (bile juice) – makes the food alkaline and emulsifies fat, 4. Pancreatic lipase – breaks down emulsified fat, 5. Trypsin (pancreatic juice) – digests protein, 15. How is the small intestine designed to absorb food?, The inner wall of small intestine has many small fingers like projections called villi. They absorb, digested food and pass it to the blood around them., 16. What are the different ways in which glucose is oxidized to provide energy in various, organisms?, A. ANAEROBIC RESPIRATION: In yeast cell glucose is breakdown in the absence of oxygen, to form ethyl alcohol and carbon dioxide along with 2ATP and 56 Kcal of heat energy., Glucose → 2 pyruvate →carbon dioxide +ethanol + 2ATP +56Kcal Cell absence of oxygen (2, carbon compound), B. OXYGEN DIFFICIENT RESPIRATION: In skeletal muscles of humans, when there is, deficiency of oxygen glucose is converted into lactic acid, Glucose → 2 pyruvate → Lactic acid + 2ATP +56Kcal Cell lack of oxygen (3 carbon compound), C. AEROBIC RESPIRATION: In the cells of higher organisms, in mitochondria, presence of, oxygen glucose is converting into CO2 and H2O. In this process large amount of energy is, liberated. Glucose → 2 pyruvate → 6CO2 + 6H2O +38ATP + 686Kcal Cell presence of energy, 17. What causes muscle cramps?, During sudden activities because of oxygen deficiency pyruvate is converted in to lactic acid. This, build-up of lactic acid causes muscle cramps, 18. The rate of breathing in aquatic animals is faster than terrestrial organisms. Why?, Aquatic animals breathe the oxygen dissolved in water. But the amount of dissolved oxygen in, water is very less compared to air. To get sufficient oxygen they breathe faster., 19. How is oxygen and carbon dioxide transported in human beings?, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 45

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Human beings have haemoglobin in blood. Haemoglobin has affinity to oxygen. So it carries, oxygen to the cells. But the carbon dioxide is water soluble. It is brought back by blood., 20. Explain the circulation of blood in our heart., Lungs (oxygen rich blood) ------ pulmonary veins ----- left atrium ----- left ventricle ----- aorta ----body, Body (de oxygenated blood) ----- vena cava ------ right atrium ----- right ventricle ----- pulmonary, arteries ----- lungs, 21. Reptiles and amphibians have 3 chambered hearts where as birds and mammals have, four chambered heart. Why?, Birds and mammals are warm blooded. They need more energy to maintain their body, temperature. Presence of septum makes the heart four chambered. This avoids the mixing of, oxygenated and deoxygenated blood. This will help to generate more energy. But amphibians and, reptiles are cold blooded. They have no need to maintain body temperature. So they have 3, chambered hearts., 22. Differentiate between arteries and veins., Arteries, 1. they carry blood from heart to body, 2. they are thick walled to withstand high, pressure, 3. they do not have valves, 23. What is double circulation?, , Veins, 1. they carry blood from body to heart, 2. they are thin walled, 3. they have valves to avoid backflow of blood, , In vertebrates except fishes, blood flows twice through the heart. This is called double circulation., 24. Write the important components of blood and their functions., 1. Plasma: It helps in the transport of nutrients, salt waste materials, hormones and antibodies., 2. Red blood corpuscles: helps in the transportation of oxygen., 3. White blood corpuscles: helps in protection by destroying disease causing micro organism, 4. Platelets: help in controlling leakage of blood by clotting, 25. Name transporting fluid other than blood. Write its function., Lymph is a colourless transporting fluid present in our body. 1. It carries absorbed fat from, intestine. 2. It also drains excess fluid from extracellular spaces to blood, 26. What is translocation?, The process of transportation of soluble product of photosynthesis is called translocation., 27. What is transpiration? How is it essential for plants?, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 46

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The process of loss of water from plant body in the form of water vaporous especially through, stomata is called transpiration. It helps in absorption and upward movement of water and minerals., It also helps in temperature regulation., 28. Explain the process of transport of water in plants., Root, stem and leaves of plant are interconnected with xylem tissue. Water from soil enters roots, because of osmosis. Then it is carried up to the leaves by transpiration pull. During night root, pressure helps in transport of water., 29. How is food transported through phloem?, Sucrose is transferred to phloem by using ATP. This increases osmotic pressure inside the tissues., So water will move in to it. This creates a pressure and moves sugar to the region of less pressure., Hence the food moves., 30. Differentiate between the material transport in xylem and phloem., Xylem conduction, 1. Transports water and minerals., 2. It is also called ascent of sap., 3. It takes place by using physical forces like, transpiration pull and capillary rise., 4. It takes place only in upward direction., , Phloem conduction, 1. Transports food and amino acids., 2. It is also called translocation of food., 3. It takes place due to osmotic pressure, created by using energy., 4. It takes place in both upward and downward, direction., , 31. What is excretion?, The process of removal of nitrogenous waste substances from produced during metabolic, activities of the body is called excretion., 32. Name the structural and functional unit of human kidney?, Nephrons are the structural and functional units of our kidney., 33. Describe the structure and functions of nephrons., Structure: 1. it has a cluster of capillaries called glamorous 2.glamarulous is associated with cup, shaped filtering unit called Bowman’s capsule 3. It is connected to tubular part 4. At the end tubes, open to a collecting duct, Function: nephrons filter metabolic wastes from blood. They produce urine and pass it out., 34. How do plants excrete?, Plants excrete, 1. Transpiration 2. Shedding dead parts 3.By producing resins, gums 4.Throw out through roots., 35. What are the excretory substances excreted in human beings?, Urea and uric acid, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 47

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CHAPTER 7 - CONTROL AND COORDINATION, 1. Write the general scheme of how nerve impulses travel in the body., Receptors (chemical impulses) -----Dendrites (electrical impulses) ----Cell body----Axon----Nerve ending (chemical impulses) ----Dendrites., 2. What is synapse?, The gap between the nerve endings of one neuron to the dendrites of the next neuron is called, synapse., 3. What is the role of the brain in reflex action?, After the reflex action spinal cord reports the brain regarding the action. Brain will store and, analyze the information. This will help in coordination in future., 4. What is reflex action? Give examples. Name the center of reflex action., A sudden reaction to the particular action in our environment is called reflex action. Example withdrawing our hands after touching a hot object., Spinal cord is the center of reflex action., 5. Write the sequence of the events that take place during reflex action., Receptor ---- sensory neuron----- relay neuron ----- motor neuron ----- effectors (muscles), 6. Write the functions of the following parts of human brain., 1. Fore brain (cerebrum): helps to understand the information received by sensory organs. It, is the thinking part of our brain., 2. Medulla: controls involuntary actions like blood pressure, salivation and vomiting., 3. Cerebellum: it is responsible for precision of voluntary activities and maintaining the, posture and balance of the body. Example: bicycle riding, walking and picking up a pencil, e.t.c., 7. Name different tropic movements in plants and give examples., 1. Phototropism: light stimulated movement. Example - bending of stem towards light,, bending of roots away from light., 2. Geotropism: growth due to gravity. Example – upward growth of shoots and downward, growth of roots., 3. Hydrotropism: water stimulated movement. Example: roots growing towards water., 4. Chemotropism: growth stimulated by chemicals. Example - growth of pollen tube towards, the ovary., 8. What are directional movements? Give examples., In plants some growth is directional and the part will appear as if it is moving. These are called, directional movements. Example – movement of tendrils towards the support, movement of, roots towards water, growth of pollen tube towards the ovary, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 48

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9. List about the important endocrine glands, their secretion and their functions in, animals:, S., N, , ANIMAL, HORMONE, , ENDOCRINE, GLAND, , FUNCTION, , 1., , Growth, hormone, , Pituitary, , Stimulates growth in all organs., , 2., , Thyroxin, , Thyroid, , Regulates metabolism for body growth., , 3., , Insulin, , Pancreas, , Regulates blood sugar level., , 4., , Testosterone, , Testis, , Development of male sex organs., , 5., , Estrogen, , Ovary, , Development of female sex organs., , 6., , Adrenaline, , Adrenal, , Coordinates respiration heart beat during emergency., , 7., , Releasing, hormone, , Hypothalamus, , Stimulates pituitary gland to release hormones., , 10. Name some plant hormones and write their functions., 1. Auxins: Increase the length of the cell, 2. Gibberellin: Helps in growth of stem., 3. Cytokinins: Promotes cell division in rapid growing parts like fruits and seeds., 4. Abscisic acid: Inhibits growth, ex- wilting of leaves., 10. Why should we use iodized salt in our diet?, Iodine helps the proper secretion of thyroxin hormone. This hormone regulates our metabolism. If, iodine level decreases it causes goiter, 11. What is the reason for the irregular sugar level in our blood and how can we control it?, Irregular sugar level in our blood is due to the decrease in the insulin hormone. This condition is, called diabetes. It can be controlled by taking proper quantity of insulin., 12. What is the effect of deficiency of pituitary hormone in puberty?, It causes dwarfism, 13. Explain, how these movements take place in plants?, 1. Closing of touch me not leaves: The change in the water level of the cells causes wilting, 2. Growing of tendrils around the support: Auxin secretes more in the shoots that are away, from the support. So they grow long and hug around the support., 3. Bending of shoots is towards light: Auxin secretion increases in shady region. Shoot of that, side grows long and bends towards light., 14. How does our body respond during adrenaline secretion?, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 49

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During adrenaline secretion breathing rate increases and heartbeat also increases. This increases, the blood flow in muscles and supplies more oxygen to work faster., , 15. Differentiate between nervous and hormonal mechanisms in animals., Nervous mechanism, 1. They are carried out by combination of, electrical and chemical impulses., 2. Network of nerves will help in transmission, 3. They can reach only to the cells that are, connected by neurons., 4. It takes some time to generate impulses., 5. They are controlled by brain and spinal, cord., , Hormonal mechanism, 1. They are carried out by chemical impulses, in the form of hormones secreted by endocrine, glands., 2. Hormones are carried through blood., 3. They can reach all parts our body., 4. They are very quick, 5. They are controlled by hypothalamus and, endocrine glands, , 16. How are involuntary actions different from reflex actions?, Involuntary actions, 1. They are independent actions predesigned, by our body., 2. They are controlled and carried out by, medulla., , Reflex actions, 1. They are sudden actions to the stimulus in, our environment., 2. They are controlled and carried out by our, spinal cord., , CHAPTER 8 – HOW DO ORGANISM REPRODUCE, 1. What is reproduction? What is its importance?, The ability of an organism to create a new organism which looks like themselves is called, reproduction. It is needed for the continuation of the species on earth., 2. Why is D.N.A copying an essential process of reproduction?, D.N.A carries essential information for protein synthesis. Organisms need D.N.A transfer to, possess the characters of their species. So to pass hereditary information from generations to, generations D.N.A copying is necessary., 3. Mention different types of asexual reproduction methods with examples., Type, , Definition, , DDPI Bangalore Rural Dist, , Example, , Science Study Package 2021-22, , fig, , pg. 50

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1. Binary fission, , Single cell splits in to two, cells, , Amoeba,, , Leshmania, , 2. Multiple, fission, , A single cell splits in to too, many cells, , Plasmodium, , 3. Fragmentation, , Multi cellular organism, breaks in to many pieces, after maturation, , Spirogyra, , 4. Regeneration, , In fully differentiated, organisms new organisms, are born by their body parts, , Planaria, , 5, , An outgrowth in the body, grows to new organism, , Yeast, Hydra, , 6. Vegetative, propagation, , New plants are produced by, root or stem or leaves of, plants, , 7. Spore, formation, , Small dusty structures are, formed in sporangia. They, develop in to new organism, when they get moist surface, , Sugarcane,, Rose, Grapes,, Banana,, Bryophyllum, Rhizopus, , Budding, , 4. Why do some plants reproduce through vegetative propagation?, 1. To produce plants from those who lost capacity to produce seeds 2. These plants produce, flower and fruit earlier 3. Produce genetically similar plants., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 51

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5. How will organism be benefited if it reproduces through spores?, 1. Spores can survive for long time enduring environmental variations., 2. They are minute and be dispersed easily for longer distance., 3. They are produced in large quantity, 4. They will germinate easily and quickly after getting favorable conditions., 6. Complex organisms cannot reproduce through regeneration. Why?, Complex organisms are made of much type of cells, tissues, organs and organ systems. It is not, possible for a piece to differentiate in to such complex structure, 7. How do Variations occur? How are variations useful?, Errors during replication of DNA, mutations and combination of parental genetic materials cause, variations. Variations are useful for ensuring the survival of the species., 8. What are the advantages of sexual reproduction over asexual reproduction?, Sexual reproduction, , Asexual reproduction, , 1., , Two individuals are involved, , 1.Only one individual is involved, , 2., , Variations are seen, , 2. Variations are not seen, , 3., , Offspring’s are different from parents, , 3. Offspring’s are same as parents., , ., 9. What are the advantages of sexual reproduction?, The advantages of sexual reproduction include, 1. Induces variation in a population., 2. New individuals with new characters are produced every time., 3. Maintains the chromosome number of the species by meiotic division., 4. During the course of evolution may lead to speciation, 10. What is Pollination?, Pollination is the process of transfer of pollen from anther to stigma., 11. What is fertilization?, Fertilization is the process of fusion of male and female gametes., 12. List the changes that occur in flower after fertilization?, The changes that occur in the flower after the fertilization are, 1. The ovule is converted to seed, 2. The ovary develops in to fruit., 3. The petals, staples, stamens, style and stigma shrivel and fall off., 13. Differentiate between self-pollination and cross-pollination in flowers, Self pollination, , DDPI Bangalore Rural Dist, , Cross-pollination, , Science Study Package 2021-22, , pg. 52

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1., The transfer of pollen from anther, of flower to the stigma of the same flower is, called self pollination, , 1., The transfer of pollen from anther of, one flower to the stigma of the another flower is, called cross pollination, , 2. Self pollinating flowers show less, variation, , 2. Cross pollinating flowers show more, variation, , 14. Differentiate between unisexual flowers., Unisexual flower, 1. They possess either male or female part i.e, stamen or pistil., 2. They can have only cross pollination., 3. Example – watermelon, papaya, maize., coconut, , Bisexual flower, 1. They possess both male or female parts i.e, stamen and pistil., 2. They can have both self and cross, pollination., 3. Example – hibiscus, mustard, may flower, , 15. What are the changes seen in girls at the time of puberty?, The changes that are seen in girls at the time of puberty are, 1. Increase in breast size and darkening of nipples., 2. Appearance of hair in genital area, under arms, face, hands and legs., 3. Increase in size of uterus and ovaries., 4. Beginning of menstrual cycle., 5. Secretion of oil in skin, which results in pimple formation., 16. What are the changes seen in boys at the time of puberty?, The changes that are seen in boys at the time of puberty are, 1. Appearance of hair in genital area, under arms, face, hands and legs., 2. Secretion of oil in skin, which results in pimple formation., 3. Thick hair growth on face., 4. Their voices begin to crack., 5. Penis occasionally becomes enlarged and erect., 17. Why are testes located outside the abdominal cavity in the scrotum? Mention the, functions of hormones secreted by it?, The testes are located outside the abdominal cavity because sperm formation requires a lower, temperature than the normal body., ., 18. Mention the function of different parts of the female reproductive system., Ovary - to produce eggs, that are required during fertilization. Produces estrogens and, progesterone, Oviducts –provides space for fertilization and helps in transporting the sperms towards egg, Uterus - helps in nurturing the fertilized egg/embryo., Vagina- helps in the entry of sperms, ., 19. Explain the functions of each structure in human male reproductive system., Testes - produces sperms and secretes testosterone to regulate the secondary sexual characters in, boys, Vas deferens - Deliver sperms to urethra, Prostate glands and seminal vesicles- secrete fluid for easy transport of sperms and provide, nutrition, Penis- helps in the ejaculation of sperms to female body., 20. Explain the structure and functions of placenta?, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 53

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Structure: Placenta is a special tissue present in the uterine wall of the mother. It contains on the, embryo side many villi. On the mother’s side are blood spaces which surround the villi. The, presence of villi provides a large surface area for glucose and oxygen to pass from mother to the, embryo., Function: Placenta helps the embryo to get nutrition and oxygen from mother. It also helps to, remove waste products generated by the embryo, 21. What is menstruation? What is its significance?, Discharging unfertilized egg with nourishing tissues from uterus at regular intervals is called, menstruation. This will help uterus to prepare freshly to receive embryo., 22. What is contraception? Why does a person need to adopt it?, The method that avoids pregnancy is called contraception., Contraceptive methods are mainly adopted because of the following reasons:, 1. To prevent unwanted pregnancies., 2. To maintain proper intervals between pregnancies, 3. To control population rise or birth rate., 4. To prevent the transfer of sexually transmitted diseases., 23. Mention the different contraceptive methods. How do they work?, The different contraceptive methods are1. Condoms and diaphragms, 2. Copper T, 3. Surgical method – vasectomy and tubectomy, avoid the fusion of gametes, 4. Oral contraceptive pills – causes hormonal imbalance which will stop the release of eggs., 24. What are sexually transmitted diseases? Give examples, The diseases caused during sexual contact are called sexually transmitted diseases. ExampleBacterial diseases - Gonorrhea, Syphilis,, Viral diseases – Warts and HIV-AIDS, 25. What is pre-natal sex determination? Why is it banned?, The process of determining sex of a child before birth is called pre-natal sex determination., The male to female ration in the country is less. To reduce this gap and also to save the girl child, the pre-natal sex determination is banned., , CHAPTER 9 - HEREDITY AND EVOLUTION, 1 What is Heredity?, Heredity is the transmission of characters or traits from the parents to their offspring., 2. What is Variation?, Variation is the difference in the characters or traits among the individuals of a species., 3. Why Mendel chose pea plants for his experiments?, 1. Pea plants can grow in pots and on land easily., 2. Pea plants have very short life cycle., 3. It can produce more number of seeds., 4. It produces bisexual flowers which undergo self & cross pollination., 5. It shows more number of characters (traits) which can easily inherited., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 54

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4. What are the differences between Inherited Traits and Acquired Traits?, Acquired Traits, Inherited Traits, -These are somatic variations., -These are genetic variations., -Acquired traits develop due to the effects of, -Inherited traits develop due to reshuffling of, environmental factors, use and disuse of organs, genetic material and mutations., and special (conscious) efforts., -These traits develop throughout the lifetime of an -These traits are transferred (inherited) by the, individual and die with the death of that, parents to their offspring. These do not die, individual., but are passed on to the next generation., -Example—Learning of dance, music, etc, and -Example—Attached or free earlobe and, muscular body of a wrestler., curly hair., 6. What is Mendel’s Monohybrid Cross? Explain., A cross made between two plants having one pair of contrasting character is called monohybrid, cross., 7. How do Mendel’s experiments show that traits may be dominant or recessive?, Mendel got all tall in F1 generation when he crossed pure tall with pure dwarf. In F2 generation he, got tall and dwarf in 3:1 ratio. This shows that F1 plants were mixed tall, and tallness was, dominant. He got dwarf only in F2 as the gene was recessive and expressed only in plants with, pure genes., 8. Mention the phenotypic and genotypic ratio of Mendel’s monohybrid cross, Phenotypic ratio of F2 plants- 3:1, 3tall: 1short, Genotypic ratio of F2 plants – 1:2:1, 1pure tall, 2 mixed tall, 1 pure short, 9. Write the dihybrid cross of yellow round with green wrinkled seed bearing plants, , Yellow round: Green round: Yellow wrinkled: Green wrinkle, 9, , :, , 3, , :, , 3, , :, , 1, , 10. How do Mendel’s experiments show that traits are inherited independently?, Mendel crossed green round seeded plant with yellow wrinkled one. In F2 generation he got, yellow round 9, yellow wrinkled 3, green round 3, and green wrinkled 1. This shows that yellow, colour is independent of round nature, green is independent of wrinkled nature, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 55

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11. How is sex of a baby determined in human beings?, In humans, male have XY chromosomes, and female have XX chromosomes. If the child gets X, from both father and mother it will be a girl. If it receives Y from father and X from mother it will, be a boy., 12. What is speciation? What are the factors that cause speciation?, Origin of new species from pre existing species is called speciation. Natural selection, genetic, drift, decreased gene flow, geographic and reproductive isolation are the causes for speciation., 13. Explain genetic drift with example., Variation that provides diversity without any adaptation is called genetic drift. In a population of, red beetles variation produced blue colored beetles. Accidentally an elephant stepped on the bush, and all the red beetles died. Blue coloured survived and continued without any favorable variation., 14. “Favorable variations lead to origin of new traits in a population by natural selection”., Explain with example., In a population of red beetles variation produced green beetles. As the green beetles were not seen, by crows they survived and their progeny continued. But the red ones were eaten and slowly, vanished., 15. “Acquired traits are not inherited over generations”. Explain with example., A bush of beetles suffered with plant disease. This reduced the leaves and the weight of beetles, that fed on leaves. This continued for few generations. But after many years the disease cured and, leaves reappeared. So beetles gained their weight. This is because they have not under gone gene, variation., 16. What are homologous and analogous organs? How do they help in studying evolution?, Homologous organs: organs that have same structure and perform different functions are, homologous organs. Ex – legs of frog and lizard, fore limbs of bird and man., Analogous organs: organs that have different structure but perform same function are analogous, organs. Ex – wings of bat and birds., By studying homology and analogy we can know about their ancestors, and if we keep on going, back we will come to know non living things have given rise to living., 17. Wings of birds and bats are analogous. Justify and comment on their origin., Wings of bats have skin folds stretched mainly between elongated fingers. But wings of birds have, feathery covering all along the arm. Their designs and structural components are different but they, look similar as they have common use for flying. So they have different ancestral origin, 18. What are fossils? How do they help in studying evolutionary relationships?, Fossils are the preserved traces of living organisms., 1. We can compare the organ structure of current with extinct one., 2. We can find the time of origin of different species., 3. We can find the intermediate stages of evolution of complex organs/ organisms., 4. We can study the Causes for evolution by comparing past environmental conditions., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 56

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19. Name the two techniques used to find the age of the fossils. Explain in brief., 1. Relative dating – estimating the age by relating it with age of the layer of earth., 2. Absolute dating – estimating the age by calculating the amount of isotopes of a element present, in the fossil., 20. Birds are closely related to reptiles. How?, The study of dinosaur’s fossils tells us that they had feathers. Feathers provided insulation to cold, weather. They were reptiles. Birds also have feathers for flying. As the structures are same we can, say birds are closely related to reptiles, 21. “Very dissimilar looking structures evolve from common ancestral design “. Explain, with an example., Artificially selected wild cabbage leads to evolution of many vegetables. i.e. Short distant leavescabbage, large leaves- kale, swollen stem- kohlrabi, sterile flower- cauliflower, flower with, arrested growth- broccoli., 22. Name the tools used for tracing evolutionary relationship., Excavation, time- dating, studying fossils and D. N.A sequences are the tools used to study, evolutionary relationships., 23. How is equal genetic contribution of male and female parents ensured in the progeny?, During sexual reproduction offspring will be formed by the union of male and female gametes. It, will receive equal halves of genetic material from both of its parents. So the genetic contribution is, ensured., 24. Why are acquired traits inherited by future generations of an organism?, Acquired traits will not bring about any change in DNA of germ cells. Hence they cannot pass on, to the future generation., 25. How are the areas of study – evolution and classification - interlinked?, Classification is grouping organisms on structural similarities and differences. In evolution we use, these structural comparisons to find origin and relationships of organisms. Hence they are, interlinked., 26. Why the small number of surviving tigers is is a cause of worry according to genetics., Small number of tigers limits the gene pool and gene flow of the species. This will affect the, variation in population. As variation is affected, the chances of their survival are worried., 27. Explain in brief about human evolution., Human originated from Africa. Because of migration, separation adaptations and mixing many, races were formed. But all of them are same species., , CHAPTER 15 - OUR ENVIRONMENT, 1. What are the components of an ecosystem?, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 57

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a) Biotic components: Plants, animals and microorganisms. b) A biotic components: water, soil,, wind, temperature etc., 2. What is biodegradable and non-biodegradable substance? Give example., The substances which are easily degraded by the enzymes of saprophytes and get converted into, simpler substances are called biodegradable substances. Ex: Paper, cloth, agricultural waste,, sewage water, kitchen waste etc.,, The substances which are not easily degraded by the enzymes of saprophytes are called non –, biodegradable substances. Ex: DDT, plastic, pesticides, fertilizers etc, 3. What is the role of decomposers in the ecosystem?, Organisms that feel on dead plants and animals are called decomposers. EX: bacteria, fungi etc., They breakdown the complex organic compounds present in the dead remains into simpler, substance and obtain nutrition form them. These substances are released into the soil and the, atmosphere., 4. What is food chain?, The unidirectional flow of energy from one organism to another in the form of food is called food, chain. Grass --- insects --- snake --- hawk, 5. What are tropic levels? Give an example of food chain and state the tropic levels in it., Each step of food chain through which food is transferred is called tropic level. Each food chain, contains three to four tropic levels. Tree --- rabbit --- snake --- hawk (producers) (1st consumers), (secondary consumers) (tertiary consumers) 1st tropic level 2nd tropic level 3rd tropic level 4th, tropic level T1 T2 T3 T4, 6. Why green plants are called producers?, All green plants and blue green algae produce food by the process of photosynthesis and this is the, source of nutrition for rest of animals present in the ecosystem. Hence plants are called producers., 7. What is terrestrial food chain and aquatic food chain? Give example, i) Terrestrial food chain: The food chain present o the land is called terrestrial food chain., Ex: Grass --- insects --- snake --? Hawk, ii) Aquatic food chain: The food chain present in different water bodies is called aquatic food, chain., Ex: Phytoplankton --- zooplanktons --- fish --- shark, 8. What is food web? Give one example. Inter connecting food chains of an ecosystem is called, food web, because each organism is a part of two or more food chains., 9. Grass ------- grasshopper ------ frog ----- snake ----- eagle,, Refer the above food chain and answer the following., A. Name the producer in this food chain., B. Who is the secondary consumer here?, C. Who has the highest pesticide content in the body?, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 58

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D. Whom do you find in the fourth tropic level?, A. Grass B. Frog C. Eagle D. Snake, 10. The flow of energy is unidirectional in an ecosystem. Why?, Because, only 10% of the energy is transferred and 90% will be lost in the form of heat. The, energy absorbed in any tropic level will not revert back to the previous level. So it is, unidirectional., 11. Plants --- sheep --- human beings, In the following food chain, the availability of energy to human being is 5 kJ. What is the, amount of energy present in the producers’ level?, 500 J, 12. What will happen if we kill all the organisms in or tropic level?, If we kill all the organisms in one tropic level, the lower tropic level will grow more in number, and the higher tropic level will not survive because flow of energy from one tropic level to other, will not take place., 13. What is bio magnification? Give example., It is a phenomenon of progressive increase in the concentration of toxic substance at each, progressive tropic level. Ex: Pesticides like DDT sprinkled on plants enters the body of humans, through food chain. Bio magnification of DDT Water ---Phytoplankton --- fish --- birds, 14. What is the importance of food chain and food web?, i) It helps in the transfer of energy form one tropic level to another., ii) Provides information about biotic components of an ecosystem., iii) It helps to analyses the interaction between the organisms of an ecosystem, 15. Usually more than four tropic levels do not exist in an ecosystem. Why?, The number of tropic levels in an ecosystem is restricted up to 4 – 5 because only 10 percent of, the energy is transferred to each tropic level from the lower tropic level. Energy present in the last, tropic level is not enough to the existence of next tropic level., 16. What is ozone? How does it affect any ecosystem?, Ozone is a tri atomic molecule i.e., made up of three atoms of oxygen joined together. Its, molecular formula is O3. It can affect any ecosystem in the following ways i) It forms thin sheet, over Earth’s atmosphere and it protects against ultraviolet rays. ii) If ozone layer is depleted, UV, radiation enters the Earth’s atmosphere and causes eye irritation, skin cancer in humans reduce, productivity in plants etc.,, 17. What are the consequences of ozone layer depletion?, i) UV radiation enters into the atmosphere causes skin cancer, cataract in humans., ii) It affects the growth and physiological function of both plants and animals, iii) Causes variation in the number of phytoplankton, through which it affects the ecosystem., iv) Causes change in the composition of gases in the atmosphere., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 59

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18. What are the reasons for the depletion of ozone layer?, The chemicals like, chlorofluorocarbons (CPC’s), carbon tetra chloride, halogens, methane,, aerosols, etc., are responsible for ozone layer depletion., 19. Give any two ways in which biodegradable substances would affect the environment., 1. Decomposition of biodegradable substances may release certain gases in the atmosphere and, they may pollute the environment., 2. They may become the breeding places of files and other pests, their causing diseases., 20. List two methods of safe disposal of the non-biodegradable waste., i) By underground dumping (landfills) ii) By recycling iii) Composting, iv) Biogas production v), Incineration – bringing of substance at high temperature to form ash., 21. What are the advantages of cloth bags over plastic bags during shopping?, Advantages of cloth bags over plastic bags during shopping are i) Cloth bags are biodegradable, thus can be easily decomposed by microorganisms ii) Cloth bags can be used again, can be, washed and do not causes any harm to the environment. iii) Plastic bags are non-biodegradable, and hence can pollute the environment., 22. Why should biodegradable and non-biodegradable wastes be discarded in two separate, dustbins? Biodegradable materials are broken down by microorganisms in nature into simple, harmless substances. Non –biodegradable materials need a different treatment like heat an, temperature for disposal and hence, both should be discarded into two different dustbins., 23. We often observe domestic waste decomposing in the residential colonies causes, problems. Suggest ways to make people that the improper disposal of waste is harmful to the, environment., i) Banners and signboards can be hanged in residential colonies in order to educate people about, the ill effects of improper waste disposal, ii) Street plays can be organized for highlighting this issue., 24. How can you help in reducing the problem of waste disposal? Give any tow methods., i) Minimize the use of disposable items., ii) Recycle the materials to be used., iii) Reduce the usage of non-biodegradable substances like plastic, polythene bags etc.,, iv) Reduce the usage of non-biodegradable pesticides etc.,, 25. What are the advantages of waste management?, 1. Clean Surroundings 2. Decrease in amount of waste. 3. Prevention of Soil Pollution 4. Can, control the spreading of communicable diseases by insects and rats.5.Production of manure,, biogas, and electricity from waste., 26. List out some steps to manage wastes., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 60

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1. Produce less waste, 2.Separate Biodegradable and Bio-degradable materials, 3.Make compost, or biogas from biodegradable wastes, 4. Reduce or Reuse of Recycle non biodegradable waste., , CHAPTER 16 – SUSTAINABLE MANAGEMENT OF, NATURAL RESOURCES, 1. What do the presence of coli form bacteria in water bodies indicate?, It shows the contamination of water by fecal substance., 2. Give any four reasons to stop the usage of firewood as a source of fuel., 1) It leads to cause deforestation 2) It has low calorific value 3) It requires in large quantity, 4) It leads to cause high pollution., 3. Give any two reasons for the failure of sustainable management of ground water., i) Use of ground water throughout the year (it is recharged only during rainy reasons) ii) Rain, water technique is not properly implemented., 4. Name any two materials, which can be easily recycled and generally thrown out, as trash., Used paper, polythene bags, metal waste, etc., 5. What is Rainwater harvesting?, Collection of rain water through different methods and use throughout the year is called rain, waters harvesting., 6. What is eutrophication?, A number of nutrients such as nitrogen and phosphorus reach the lake through the stream. It, causes natural aging of a lake due to increasing of plants is called eutrophication., 7. What is sustainable management of natural resources?, Controlled use of resources without disturbing nature is called management of resources. It also, makes the resources available for future generation., 8. Mention any two major benefits of dams., i) Implementation of irrigation project. ii) Production of electricity., 9. What is the purpose behind Amrita Devi Bishnoi national award?, In 1731, Amrita Devi Bishnoi along with 363 other people scarified their life for the protection of, khejri trees in khejrali village near Jodhpur in Rajasthan. So to honor their sacrifice every year, Amrithadevi Bishnoi award is awarded to the one who made outstanding work in the field of, wildlife conservation, 10. Suggest some consequences due to the loss of biodiversity?, The food chain and food webs will get disturbed. Resources will not be available for the next, generation., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 61

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11. List two measures that you would suggest for the better management of water resources., Two measures for the better management of water resources are i) Rain water harvesting ii), Construction of dams., 12. List any four stakeholders, who may help in conservation of forests., The stake holders who may help in conservation of forest are 1.Locals living in villages near the, forest area 2.Industrialists practicing recycling. 3. Wildlife and nature enthusiasts 4. Forest, development of the government., 13. List any four harms caused due to destruction of forests., i) Decrease in the forest produce ii) adverse effect on quality of soil iii) Adverse effect on sources, of water iv) Loss of wild life, thus adverse effects on ecosystem, 14. Mention any two reasons for which environmentalist protested against raising the height, of “Sardar Sarovar Dam” on river Narmada., 1. Submergence of additional land 2.inadequate compensation 3.disappointed rehabilitation 4., Loss of biodiversity, 15. What are the poisonous gasses released during the burning of fossil fuel?, Oxides of carbon sulphur and nitrogen, 16. What changes can you make in your habits to become more environmental friendly?, The following changes can be made to be environmental friendly 1) Check the wastage of water,, close the tap properly. 2) Use solar water heater and cookers, install solar panel for electricity. 3), Reduce the garbage by not throwing such items. 4) Switch over to CFL and LED lights to save, electricity 5) Use cloth bags instead of polythene bags., 17. Why do we conserve forest and wild life?, i) Forests are biodiversity hot spots: number of species found in an area measures it. ii) Forests, help in protection of land and retaining soil water. iii) Forest checks floods and maintain, ecosystem. iv) Wild life is important because v) they provide great aesthetic value for human, beings. vi) They help in maintaining ecological balance., 18. Suggest some approaches towards the conservation of forests., i) A forestation – growth of forest in new open area. ii) Deforestation should be banned. iii) People, should be made more aware about importance of forest iv) There should be proper law’s for, exploitation of forest resources. v) Growth of agricultural forest., 19. Reuse is better than recycling of materials give reasons to justify the statement., Reduce is better than recycling because, i) Reuse of material does not use any energy. ii) It, reduces the stress on environment. iii) Things are maximally utilized, as they are used again and, again, instead of being thrown away., 20. Why do we need alternative source of energy?, Our resources are limited and with the increase in population the demand for all the resources, in increasing in exponential rate. So to save these resources we need alternative sources of, energy., 21. What are 5R practices which protects environment. Explain briefly., DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 62

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1) Refuse 2) Reduce 3) Reuse 4) Repurpose 5) Recycle, 1) Refuse: Refuse to buy products that can harm you and the environment. Say no to single use, plastic carry bags., 2) Reduce: This means that you use less. Save electricity by switching off lights and fans when, they are not required. Save water by repairing leaky taps. Do not waste food., 3) Reuse: This is actually even better than recycling because the process of recycling uses some, energy you simply use things again and again. Instead of throwing away used envelopes, you can, reverse it and use it again. The plastic bottles in which you buy various food items like jam and, pickle can be used for storing things in the kitchen., 4) Repurpose: This means when a product can no more be used for the original purpose, think, carefully and use it for some other useful purpose. For eg: Caps with broken handles can be used, to grow small plants and as feeding vessels for birds., 5) Recycle: This means that you collect plastic, paper, glass and metal items and recycle these, materials to make required things., 26. Why do we need to manage our resources carefully?, Because, i) These are not continuously available ii) The demand for these resources keeps on, increasing. iii) These resources also need to be preserved for future generations iv) These are, equally distributed amongst the rich and the poor., 27. Write some of the simple choices that can make a differences in our energy consumption, patterns., Some of the simple choices that can make a difference in our energy consumption ways and, proved to be environmental friendly are. i) Walking / cycling instead of a taking a bus or driving, car. ii) Using stairs instead of a lift to climb upiii) Wearing an extra sweater rather than using a, heater which runs on electricity., 28. What was “ChipkoAndolan”? How did this Andolan ultimately benefit local people and, the environment?, The movement, which was started in Reni village in Garhwal to protect the trees by hugging them, and not allowing cutting of these trees, was called “ChipkoAndolan” i) The Chipko movement, quickly spread across communities and media and forced the government, to whom the forest, belongs, to rethink their priorities in the name of forest produce. ii) Due to participation of local, people, it led to the efficient management of forests. iii) It explains that the loss of forest is not, only influenced on forest product, but also influenced on water reservoirs and quality of the soil., 29. What are greenhouse gasses? What is the effect of increasing of greenhouse gasses in the, environment?, Carbon dioxide, Methane, CFC‟s and Oxides of nitrogen.It increases average earth’s atmospheric, temperature by trapping infrared radiations., 30. List the methods to reduce the carbon dioxide concentration in the atmosphere. a. Using, public transport. b. Using compressed natural gas (CNG). c. Increase the growth of forest and, prevent deforestation. d. Conversion of waste into compost instead of burning. e. Using bicycles, instead of motor cycle., 31. What are the advantages of storage of water under the soil (as ground water)?, DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 63

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The various advantages of underground water are 1. It does not evaporate. 2. Helps to recharge, well.3. It provides moisture for vegetation over a wide area.4. It does not provide breeding, grounds for mosquitoes like stagnant water. 5. It is protected from contamination by human and, animal waste., 32. What are the advantages behind watershed management?, 1. Increases production and income of watershed community, 2. Lowers the risk of drought and floods, 3. Increases the life of downstream dams and reservoirs, 33. Name the ancient water harvesting structures., In Rajasthan - khadins,tanks, nadis, in Maharashtra – bandharas and taals, in Madhya Pradesh and, utterpradesh – bundhis, in Bihar – ahar and pynes, Kulhs – Himachal Pradesh, in Tamilnadu – eri,, Kerala – surangam, in Karnataka – katta, 34. Forests are biodiversity hotspots. Justify., Forests have a huge number of species and are threatened by human habitation. So they are called, bio-diversity hotspots., , DDPI Bangalore Rural Dist, , Science Study Package 2021-22, , pg. 64