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CHAPTER, , 1, Basic Concepts of Chemistry, Matter, , •฀ Mixtures฀which฀contain฀different฀phases฀each฀with฀its฀, , •฀ Anything฀which฀has฀mass฀and฀occupies฀space฀is฀matter.฀, •฀ On฀the฀basis฀of฀state,฀the฀matter฀is฀classified฀into฀solid,฀, , •฀, , liquid฀and฀gaseous฀substances;฀e.g.,฀water฀in฀the฀form฀, of฀ice฀is฀solid,฀water฀is฀liquid฀and฀water฀vapour฀is฀gas.฀, , •฀, , •฀ Solids฀have฀high฀density,฀rigid฀shape,฀slight฀compres­, sibility,฀only฀slight฀expansion฀at฀atmospheric฀pressure฀, with฀rise฀in฀temperature.฀, , •฀ Liquids are฀characterised฀by฀high฀density,฀lack฀of฀defi­, , •฀, , nite฀shape,฀slight฀compressibility฀and฀slight฀expansion฀, at฀atmospheric฀pressure฀when฀heated.฀, , •฀, , •฀ Gaseous state is฀characterised฀by฀low฀density,฀indefi­, , •฀, , nite฀shape฀and฀volume,฀high฀compressibility฀and฀con­, siderable฀expansion฀when฀heated฀at฀constant฀pressure.฀, , •฀ A฀ substance฀ which฀ cannot฀ be฀ broken฀ down฀ into฀ yet฀, simpler฀ substances฀ by฀ any฀ means฀ is฀ known฀ as฀ an฀, element., , •฀, •฀, , •฀ An฀element฀consists฀of฀only฀one฀kind฀of฀atom.฀, •฀ A฀compound is฀a฀pure฀substance฀composed฀of฀two฀or฀, more฀elements฀joined฀in฀chemical฀combination฀into฀a฀, definite฀proportion฀by฀weight.฀, , •฀, , •฀ Molecules are฀identifiable฀units฀of฀matter฀consisting฀of฀, two฀or฀more฀atoms฀of฀the฀same฀element฀or฀of฀different฀, elements฀combined฀in฀a฀definite฀ratio.฀, , •฀ Atomicity is฀the฀number฀of฀atoms฀in฀a฀molecule.฀, •฀ Pure฀substances฀contain฀only฀a฀single฀substance.฀, •฀ Mixture฀is฀a฀material฀obtained฀as฀a฀result฀of฀mixing฀, two฀ or฀ more฀ substances฀ (elements฀ or฀ compounds)฀ in฀, any฀proportion฀so฀that฀the฀compounds฀do฀not฀lose฀their฀, identity,฀e.g.,฀air,฀gasoline,฀etc.฀, , •฀ A฀ mixture฀ that฀ is฀ uniform฀ throughout฀ is฀ referred฀, to฀ as฀ homogeneous฀ if฀ it฀ has฀ the฀ same฀ composition฀, throughout.฀, , own฀set฀of฀properties฀are฀referred฀to฀as฀heterogeneous., Conversion฀ of฀ one฀ substance฀ into฀ another฀ is฀ called฀ a฀, chemical change, e.g.,฀฀rusting฀of฀iron.฀, If฀a฀substance฀changes฀from฀one฀state฀to฀another฀state฀, without฀ any฀ chemical฀ change,฀ it฀ is฀ referred฀ to฀ as฀ a฀, physical change,฀e.g.,฀conversion฀of฀water฀into฀ice฀or฀, water฀vapour.฀, In฀a฀chemical฀change,฀the฀substances฀that฀are฀present฀, initially฀(the฀reactants)฀disappear.฀, One฀or฀several฀new฀substances฀(the฀products)฀appear฀, as฀the฀reaction฀proceeds.฀, The฀properties฀of฀products฀are฀different฀from฀those฀of฀, the฀reactants.฀, Energy฀ in฀ the฀ form฀ of฀ heat,฀ light฀ or฀ electricity฀ is฀ re­, leased฀or฀absorbed฀in฀the฀course฀of฀a฀chemical฀change.฀, The฀mass฀of฀an฀object฀is฀a฀measure฀of฀the฀amount฀of฀mat­, ter฀it฀contains,฀while฀the฀weight฀is฀a฀measure฀of฀the฀force฀, with฀which฀the฀object฀is฀attracted฀to฀the฀earth฀by฀gravita­, tional฀force.฀Weight฀is฀always฀proportional฀to฀mass.฀, Mass฀and฀weight฀of฀a฀substance฀are฀numerically฀equal฀, at฀the฀sea฀level.฀If฀the฀object฀is฀moved฀away฀from฀earth฀, the฀gravitational฀attraction฀decreases฀and฀therefore฀the฀, weight฀diminishes,฀but฀the฀mass฀remains฀constant.฀, , Physical Quantities and their Measurement, , •฀ Properties฀ of฀ matter฀ like฀ mass,฀ length,฀ time,฀ tem­, , •฀, •฀, , perature,฀ which฀ can฀ be฀ quantified฀ and฀ expressed฀ in฀, numerals฀ with฀ suitable฀ units฀ are฀ called฀ as฀ physical, quantities., Mass฀of฀any฀matter฀can฀be฀determined฀by฀measuring฀, resistance฀to฀movement.฀, The฀size฀of฀the฀object฀is฀measured฀in฀terms฀of฀length,฀, area฀and฀volume.฀

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1.2, , Objective Chemistry - Vol. I, , •฀ Length฀refers฀to฀one฀dimension,฀area฀to฀two฀฀dimensions฀, and฀volume฀to฀three฀dimensions฀of฀space.฀, , •฀ Time฀ is฀ another฀ term฀ of฀ measurement฀ used฀ to฀ know฀, •฀, •฀, •฀, , •฀, •฀, •฀, , how฀long฀it฀takes฀a฀process฀or฀a฀chemical฀transforma­, tion฀to฀take฀place.฀, Temperature฀is฀a฀physical฀quantity฀used฀for฀measuring฀, the฀degree฀of฀hotness฀and฀coldness.฀, Temperature฀determines฀the฀heat฀flow฀from฀a฀body฀at฀a฀, higher฀temperature฀to฀a฀body฀at฀lower฀temperature.฀, The฀ physical฀ quantities฀ which฀ are฀ derived฀ with฀ the฀, help฀ of฀ two฀ or฀ more฀ physical฀ quantities฀ are฀ called฀, derived physical quantities., e.g.,฀ density฀ is฀ a฀ derived฀ physical฀ quantity,฀ derived฀, from฀mass฀and฀volume.฀, The฀three฀aspects฀of฀the฀numerical฀result฀of฀measure­, ment฀ are฀ (i)฀ numerical฀ magnitude,฀ (ii)฀ precision฀ and฀, (iii)฀indicator฀scale.฀, The฀ physical฀ quantities฀ which฀ depend฀ on฀ the฀ size฀ of฀, the฀ sample฀ like฀ mass,฀ weight,฀ volume,฀ pressure,฀ etc.฀, are฀called฀extensive properties., The฀ physical฀ quantities฀ which฀ do฀ not฀ depend฀ on฀ the฀, size฀of฀the฀sample฀like฀temperature,฀density,฀refractive฀, index,฀surface฀tension฀viscosity,฀etc.฀are฀called฀intensive properties., , Measurement and Significant Figure, , •฀ Precision is฀the฀closeness฀of฀the฀set฀of฀values฀obtained฀, •฀, •฀, •฀, •฀, ฀, ฀, ฀, ฀, , from฀identical฀measurements฀of฀a฀quantity.฀, Accuracy is฀the฀closeness฀of฀single฀measurement฀to฀its฀, true฀value.฀, The฀digits฀in฀a฀properly฀recorded฀measurement฀are฀known฀, as฀significant figures or฀significant฀figures฀are฀the฀mean­, ingful฀digits฀in฀a฀measured฀or฀calculated฀quantity.฀, The฀greater฀the฀number฀of฀significant฀figures฀in฀a฀re­, ported฀ result,฀ the฀ smaller฀ is฀ the฀ uncertainty฀ and฀ the฀, greater฀the฀precision.฀, Rules฀for฀reporting฀the฀number฀of฀significant฀figures:฀, ฀฀(i)฀ ฀All฀ non­zero฀ digits฀ are฀ significant,฀ starting฀ with฀, the฀first฀digit฀that฀is฀not฀zero., ฀(ii)฀ ฀Zeros฀between฀non­zero฀digits฀are฀significant.฀, (iii)฀ ฀Zeros฀to฀the฀right฀of฀significant฀figures฀are฀signifi­, cant฀for฀a฀number฀less฀than฀that.฀, ฀(iv)฀ ฀When฀a฀number฀ends฀in฀zeros฀that฀are฀not฀to฀the฀, right฀ of฀ a฀ decimal฀ point,฀ the฀ zeros฀ may฀ not฀ be฀, s฀ignificant., , Calculation Involving Significant Figures, ฀, , (i)฀ W, ฀ hile฀ carrying฀ out฀ addition฀ or฀ subtraction฀ of฀ a฀, number฀of฀terms฀the฀result฀should฀be฀reported฀to฀, , ฀, , ฀, , •฀, , ฀, ฀, , the฀same฀number฀of฀decimal฀places฀as฀that฀of฀the฀, term฀with฀the฀least฀number฀of฀decimal฀places.฀, (ii)฀ ฀In฀the฀calculation฀involving฀multiplication฀or฀divi­, sion,฀the฀number฀of฀significant฀figures฀in฀the฀final฀, answer฀should฀not฀be฀greater฀than฀the฀number฀of฀, significant฀figures฀in฀the฀least฀precision฀factor.฀, (iii)฀ ฀The฀ number฀ that฀ comes฀ from฀ direct฀ count฀ of฀, ฀objects฀or฀those฀results฀from฀definitions฀is฀called฀, an฀exact฀number฀and฀is฀considered฀to฀possess฀an฀, ฀infinite฀number฀of฀significant฀figures.฀, Rounding up is฀ the฀ procedure฀ of฀ dropping฀ non­, significant฀ digits฀ in฀ a฀ calculation฀ result฀ and฀ adjusting฀, the฀last฀digit฀reported.฀The฀general฀procedure฀is฀listed฀, hereunder:฀, ฀(i)฀ ฀If฀the฀digit฀is฀5฀or฀greater฀add฀1฀to฀the฀last฀digit฀to฀, be฀retained฀and฀drop฀all฀digits฀farther฀to฀the฀right.฀, (ii)฀ ฀If฀ the฀ digit฀ is฀ less฀ than฀ 5,฀ simply฀ drop฀ it฀ and฀ all฀, digits฀farther฀to฀the฀right.฀, , Objective Questions, 1. SI฀unit฀of฀time฀is฀, (1)฀ second฀ ฀, (3)฀ hour฀, ฀, , (2)฀ minute, (4)฀ day, , 2. Which฀of฀the฀following฀statements฀is฀incorrect?฀, (1)฀ All฀elements฀are฀homogeneous, (2)฀ ฀Compounds฀made฀up฀of฀a฀number฀of฀elements฀are฀, heterogeneous, (3)฀ A฀mixture฀is฀not฀always฀heterogeneous, (4)฀ Air฀is฀an฀heterogeneous฀mixture, 3. Which฀of฀the฀following฀is฀not฀an฀element?, (1)฀ Diamond฀, (2)฀ Graphite, (3)฀ Silica฀ ฀, (4)฀ Ozone, 4. Which฀one฀is฀a฀physical฀change?฀, (1)฀ Burning฀of฀S฀in฀air, (2)฀ Burning฀of฀C฀in฀air฀, (3)฀ ฀Conversion฀ of฀ white฀ phosphorous฀ to฀ red฀, ฀phosphorous, (4)฀ Corrosion฀of฀metals฀, 5. A฀pure฀substance฀can฀only฀be, (1)฀ a฀compound฀, (2)฀ an฀element, (3)฀ an฀element฀or฀a฀compound, (4)฀ a฀heterogeneous฀mixture, 6. A฀ pure฀ substance฀ which฀ contains฀ only฀ one฀ type฀ of฀฀, atoms฀is฀called, (1)฀ an฀element฀, (2)฀ a฀compound, (3)฀ a฀solid฀ ฀, (4)฀ a฀liquid

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Basic Concepts of Chemistry 1.3, , 7. The฀number฀of฀significant฀figures฀in฀0.0500฀is฀, (1)฀ one฀, ฀, (2)฀ three, (3)฀ two฀, ฀, (4)฀ four, 8. The฀ correctly฀ reported฀ answer฀ of฀ the฀ addition฀ of฀, 29.4406,฀3.2฀and฀2.25฀will฀have฀significant฀figures, (1)฀ three฀ ฀, (2)฀ four, (3)฀ two฀, ฀, (4)฀ five, 9. The฀ correctly฀ reported฀ answers฀ of฀ the฀ addition฀ of฀, 294.406,฀280.208฀and฀24฀will฀be, (1)฀ 598.61฀ ฀, (2)฀ 599, (3)฀ 598.6฀ ฀, (4)฀ 598.614, 10. Two฀students,฀X฀and฀Y,฀reported฀the฀mass฀of฀the฀same฀, substance฀as฀7.0฀g฀and฀7.00฀g,฀respectively.฀Which฀of฀, the฀following฀statement฀is฀correct?, (1)฀ Both฀are฀equally฀accurate, (2)฀ X฀is฀more฀accurate฀than฀Y, (3)฀ Y฀is฀more฀accurate฀than฀X, (4)฀ Both฀are฀inaccurate฀scientifically, 11. The฀number฀of฀significant฀figures฀in฀π฀is฀, (1)฀ one฀, ฀, (2)฀ two฀, (3)฀ three฀, ฀, (4)฀ infinite, , •฀ Law of definite proportions:฀ Proposed฀ by฀ Proust,฀, verified฀ by฀ Strass฀ and฀ Richards.฀When฀ two฀ elements฀, combine฀to฀form฀a฀compound฀they฀combine฀in฀definite฀, proportion฀ by฀ weight฀ (or)฀ a฀ chemical฀ compound฀ has฀, same฀composition฀by฀whatever฀method฀it฀is฀prepared.฀, , •฀ Law of multiple proportions: Proposed฀ by฀ Dalton,฀, proved฀ by฀ Berzelius฀ and฀ Strass.฀ When฀ two฀ elements฀, combine฀to฀form฀more฀than฀one฀compound฀the฀different฀, weight฀of฀one฀of฀the฀elements฀combining฀with฀a฀fixed฀, weight฀of฀the฀other฀are฀in฀proportions฀of฀whole฀number.฀, , •฀ Law of reciprocal proportions: Proposed฀by฀Ritcher.฀, The฀ weight฀ of฀ two฀ or฀ more฀ substances฀ which฀ sepa­, rately฀react฀chemically฀with฀identical฀weights฀of฀third฀, element฀ are฀ also฀ the฀ weights฀ in฀ which฀ they฀ combine฀, with฀each฀other฀or฀multiples฀of฀them.฀, , •฀ Gay Lussac’s law of gaseous volumes: Volumes฀ of฀, gases฀used฀and฀produced฀in฀a฀chemical฀reaction฀stand฀, in฀ a฀ simple฀ integral฀ ratio฀ when฀ these฀ volumes฀ are฀, measured฀ under฀ the฀ same฀ conditions฀ of฀ temperature฀, and฀pressure.฀, , •฀ Berzelius Hypothesis: Equal฀volumes฀of฀all฀gases฀un­, der฀ the฀ same฀ conditions฀ of฀ temperature฀ and฀ pressure฀, contain฀equal฀number฀of฀atoms.฀, , 12. Given฀the฀numbers฀786,฀0.786฀and฀0.0786฀the฀number฀, of฀significant฀figures฀for฀the฀three฀numbers฀is฀, (1)฀ 3,฀4฀and฀5,฀respectively, (2)฀ 3,฀3฀and฀3,฀respectively, (3)฀ 3,฀3฀and฀4,฀respectively, (4)฀ 3,฀4฀and฀4,฀respectively, , •฀ Avogadro’s Hypothesis:฀ Equal฀ volumes฀ of฀ all฀ gases฀, , 13. In฀ which฀ of฀ the฀ following฀ numbers฀ all฀ zeros฀ are฀, significant?฀, (1)฀ 0.0005฀ ฀, (2)฀ 0.0500, (3)฀ 50.000฀ ฀, (4)฀ 0.0050, , •฀ Dalton’s atomic Theory: The฀observations฀of฀law฀of฀, , under฀the฀same฀conditions฀of฀temperature฀and฀pressure฀, contain฀equal฀number฀of฀molecules฀(or)฀the฀volume฀of฀, a฀gas฀at฀fixed฀pressure฀and฀temperature฀is฀proportional฀, to฀the฀number฀of฀moles฀(or฀molecules฀of฀a฀gas฀present).฀, Mathematically,฀Avogadro’s฀law฀is฀V฀α฀n.฀, multiple฀ proportions฀ led฀ to฀ the฀ formation฀ of฀ atomic฀, theory.฀, , •฀ An฀atom฀is฀the฀smallest฀indivisible฀particle฀of฀an฀ele­, ment฀that฀can฀take฀part฀in฀a฀chemical฀change.฀, , •฀ All฀atoms฀of฀a฀given฀element฀are฀identical฀both฀in฀mass฀, , answers, ฀ (1)฀ 1฀, ฀ (6)฀ 1฀, (11)฀ 4฀, , ฀ (2)฀ 2฀, ฀ (7)฀ 2฀, (12)฀ 2฀, , ฀ (3)฀ 3฀, ฀ (8)฀ 1฀, (13)฀ 3, , (4)฀ 3฀฀, (9)฀ 2฀฀, , ฀ (5)฀ 3, (10)฀ 3, , and฀chemical฀properties.฀, , •฀ Atoms฀of฀different฀elements฀have฀different฀masses฀and฀, different฀chemical฀properties.฀, , •฀ Compounds฀are฀formed฀by฀the฀combination฀of฀differ­, ent฀atoms฀in฀the฀ratio฀of฀small฀whole฀numbers.฀, , LawS oF CheMICaL CoMbInatIon, , •฀ Laws of conservation of mass: It฀ was฀ proposed฀ by฀, Lavoiser.฀ Total฀ amount฀ of฀ matter฀ in฀ the฀ universe฀, is฀ ฀unaltered฀ whatever฀ the฀ change฀ take฀ place฀ in฀ its฀, ฀distribution฀ (or)฀ the฀ sum฀ of฀ the฀ weights฀ of฀ reacting฀, substances฀are฀equal฀to฀the฀sum฀of฀the฀weights฀of฀prod­, ucts฀(or)฀matter฀can฀neither฀be฀created฀nor฀destroyed.฀, , •฀ Chemical฀reactions฀involve฀only฀combination,฀separa­, tion฀and฀rearrangement฀of฀atoms.฀, , •฀ Atoms฀are฀neither฀created฀nor฀destroyed฀in฀the฀course฀, of฀an฀ordinary฀chemical฀reaction.฀, , •฀ The฀two฀modifications฀made฀in฀the฀hypothesis฀of฀John฀, Dalton฀are฀, ฀(i)฀ an฀atom฀is฀divisible฀and฀destructive฀, (ii)฀ all฀atoms฀of฀an฀element฀are฀not฀identical฀in฀mass฀

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1.4, , Objective Chemistry - Vol. I, , Objective Questions, 14. Element฀A฀ reacts฀ with฀ oxygen฀ to฀ form฀ a฀ compound฀, A2O3.฀If฀0.359฀gram฀of฀a฀compound฀contains฀0.128฀g฀, of฀oxygen,฀atomic฀weight฀of฀A฀will฀be฀, (1)฀ 51฀amu฀ ฀, (2)฀ 43.08฀amu, (3)฀ 49.7฀amu฀, (4)฀ 47.9฀amu, 15. Oxygen฀ combines฀ with฀ two฀ isotopes฀ of฀ carbon,฀ 12C฀, and฀ 14C,฀to฀form฀two฀samples฀of฀carbon฀dioxide.฀The฀, data฀illustrates฀, (1)฀ Law฀of฀conservation฀of฀mass, (2)฀ Law฀of฀multiple฀proportions, (3)฀ Law฀of฀reciprocal฀proportions, (4)฀ None฀of฀these, 16. Suppose฀ that฀A฀ and฀ B฀ are฀ two฀ elements฀ which฀ form฀, compounds฀B2A3฀and฀B2A,฀respectively.฀If฀0.05฀mole฀, of฀ B2A3฀ weighs฀ 9.0฀ g฀ and฀ 0.10฀ mole฀ of฀ B2A฀ weighs฀฀, 10฀g,฀then฀the฀atomic฀weight฀of฀A฀and฀B,฀respectively฀is฀, (1)฀ 30฀and฀40฀, (2)฀ 40฀and฀30, (3)฀ 20฀and฀5฀฀, (4)฀ 15฀and฀20, 17. In฀the฀reaction,฀N2฀+฀3H2฀→฀2NH3,฀ratio฀by฀volume฀of฀, N2,฀H2฀and฀NH3฀is฀1:3:2.฀This฀illustrates, (1)฀ definite฀proportions฀, (2)฀ multiple฀proportions, (3)฀ reciprocal฀proportions, (4)฀ gaseous฀volumes฀, 18. One฀part฀of฀an฀element฀X฀combines฀with฀two฀parts฀of฀, another฀ element฀Y.฀ Six฀ parts฀ of฀ the฀ element฀ Z฀ com­, bines฀with฀four฀parts฀of฀element฀Y.฀If฀X฀and฀Y฀combine฀, together,฀the฀ratio฀of฀their฀weights฀will฀be฀governed฀by, (1)฀ Law฀of฀multiple฀proportions, (2)฀ Law฀of฀definite฀proportions, (3)฀ Law฀of฀reciprocal฀proportions, (4)฀ Law฀of฀conservation฀of฀mass฀, 19. Two฀samples฀of฀lead฀oxide฀were฀separately฀reduced฀to฀, metallic฀lead฀by฀heating฀in฀a฀current฀of฀hydrogen.฀The฀, weight฀of฀lead฀was฀obtained฀from฀the฀other฀oxide.฀The฀, data฀illustrates, (1)฀ Law฀of฀reciprocal฀proportions, (2)฀ Law฀of฀constant฀proportions, (3)฀ Law฀of฀multiple฀proportions, (4)฀ Law฀of฀equivalent฀proportions, 20. Chemical฀equation฀is฀balanced฀according฀to฀the฀law฀of฀, (1)฀ Multiple฀proportions฀, (2)฀ Reciprocal฀proportions, (3)฀ Conservation฀proportions, (4)฀ Definite฀proportions, , 21. Law฀of฀reciprocal฀proportions฀can฀be฀used฀to฀determine, (1)฀ Atomic฀weight฀of฀a฀gas, (2)฀ Equivalent฀weight฀of฀a฀gas, (3)฀ Molecular฀weight฀of฀a฀gas, (4)฀ None฀of฀these, 22. SO2฀gas฀was฀prepared฀by฀(i)฀burning฀sulphur฀in฀฀oxygen,฀, (ii)฀ reacting฀ sodium฀ sulphite฀ with฀ dilute฀ H2SO4฀ and฀, (iii)฀ heating฀ copper฀ with฀ conc.฀ H2SO4.฀ It฀ was฀ found฀, that฀in฀each฀case฀sulphur฀and฀oxygen฀combined฀in฀the฀, ratio฀of฀1:1.฀The฀data฀illustrate฀the฀law฀of฀, (1)฀ Conservation฀of฀mass, (2)฀ Multiple฀proportions, (3)฀ Constant฀proportions, (4)฀ Reciprocal฀proportions, 23. H2S฀ contain฀ 5.88%฀ hydrogen,฀ H2O฀ contain฀ 11.11%฀, hydrogen฀ while฀ SO2฀ contains฀ 50%฀ sulphur.฀The฀ data฀, illustrate฀the฀law฀of฀, (1)฀ Conservation฀of฀mass, (2)฀ Constant฀proportions, (3)฀ Multiple฀proportions, (4)฀ Reciprocal฀proportions, 24. 6฀g฀of฀carbon฀combines฀with฀32฀g฀of฀sulphur฀to฀form฀, CS2.฀12฀g฀of฀C฀also฀combine฀with฀32฀g฀of฀oxygen฀to฀, form฀carbon฀dioxide.฀10฀g฀of฀sulphur฀combines฀with฀, 10฀g฀of฀oxygen฀to฀form฀sulphur฀dioxide.฀Which฀law฀is฀, illustrated฀by฀them?, (1)฀ Law฀of฀multiple฀proportions, (2)฀ Law฀of฀constant฀composition, (3)฀ Law฀of฀reciprocal฀proportions, (4)฀ Gay฀Lussac’s฀law, 25. Two฀elements฀X฀(at฀mass฀16)฀and฀Y฀(at฀mass฀14)฀com­, bine฀to฀form฀compounds฀A,฀B฀and฀C.฀The฀ratio฀of฀dif­, ferent฀masses฀of฀Y฀which฀combine฀with฀a฀fixed฀mass฀, of฀X฀in฀A,฀B฀and฀C฀is฀1:3:5.฀If฀32฀parts฀by฀mass฀of฀X฀, combines฀with฀84฀parts฀by฀mass฀of฀Y฀and฀B,฀then฀in฀C฀, 16฀parts฀by฀mass฀of฀X฀will฀combine฀with, (1)฀ 14฀parts฀by฀mass฀of฀฀Y, (2)฀ 42฀parts฀by฀mass฀of฀฀Y, (3)฀ 70฀parts฀by฀mass฀of฀฀Y, (4)฀ 84฀parts฀by฀mass฀of฀฀Y, , answers, (14)฀ 2฀, (19)฀ 3฀, (24)฀ 3฀, , (15)฀ 4฀, (20)฀ 3฀, (25)฀ 3, , (16)฀ 2฀, (21)฀ 2฀, , (17)฀ 4฀, (22)฀ 3฀, , (18)฀ 3฀, (23)฀ 4

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Basic Concepts of Chemistry 1.5, , MoLe ConCept, , •฀ Atomic weight scale is฀a฀table฀that฀lists฀the฀weights฀of฀, all฀the฀elements฀relative฀to฀the฀same฀common฀standard.฀, , •฀ The฀mass฀of฀C-12฀is฀taken฀as฀standard and฀its฀mass฀is฀, assigned฀exactly฀12.฀Atomic฀mass฀unit฀(amu)฀and฀mass­, es฀of฀all฀other฀atoms฀are฀given฀relative฀to฀this฀standard.฀, , •฀ Reciprocal฀ of฀ Avogadro’s฀ number฀ is฀ known฀ as฀, Avogram., Avogram =, , 1, 1, =, = 1.67 × 10–23, N 6.022 × 10 23, , •฀ The฀number฀of฀molecules฀present฀in฀1฀cc฀of฀a฀gas฀at฀, , STP฀ is฀ known฀ as฀ Loschmidt number.฀ Its฀ value฀ is฀, 2.617฀×฀1019., twelfth฀the฀mass฀of฀one฀C­12฀atom.฀1฀amu฀=฀1.66056฀×฀, •฀ The฀ mole฀ is฀ the฀ amount฀ of฀ substance฀ containing฀ the฀, 10–24฀g.฀, same฀ number฀ of฀ atoms฀ in฀ exactly฀ 12฀ grams฀ of฀ C­12฀, Many฀ naturally฀ occurring฀ elements฀ consist฀ of฀ more฀, isotope.฀, than฀one฀isotope.฀For฀such฀elements,฀the฀atomic฀weights฀, •฀ Number฀of฀moles฀“n”฀’฀, determined฀are฀the฀average฀atomic฀weights฀of฀isotopes.฀, Weight in grams, W, = =, Molecular weight or molecular mass of฀a฀molecule฀, Gram molecular weight, M, of฀ a฀ substance฀ is฀ the฀ sum฀ of฀ the฀ atomic฀ weights฀ or฀, •฀ Weight฀of฀a฀substance฀containing฀a฀definite฀number฀of฀, atomic฀masses฀of฀atoms฀present฀in฀the฀molecule.฀, moles฀=฀Number฀of฀moles฀×฀Gram฀molecular฀weight฀, For฀ionic฀compounds฀which฀do฀not฀contain฀molecules,฀, (W฀=฀n฀×฀MW), formula฀weights฀are฀calculated฀as฀indicated฀in฀the฀for­, •฀ No.฀of฀molecules฀present฀in฀a฀given฀substance.฀, mula฀of฀an฀ionic฀compound.฀, , •฀ One฀ amu฀ is฀ defined฀ as฀ a฀ mass฀ exactly฀ equal฀ to฀ one­, •฀, •฀, •฀, , •฀ The฀ atomic฀ weight฀ expressed฀ in฀ grams฀ is฀ known฀ as฀, gram atomic weight., , •฀ Molecular฀ weight฀ expressed฀ in฀ grams฀ is฀ known฀ as฀, gram molecular weight or฀gram mole., , •฀ At฀ STP,฀ one฀ gram฀ mole฀ of฀ any฀ gas฀ occupies฀ 22.414, litres or฀ 22414 cc฀ of฀ volume.฀ It฀ is฀ known฀ as฀ gram, molar volume., , •฀ One฀ gram฀ mole฀ of฀ any฀ substance฀ will฀ contain฀฀, , Weight, × Avogadro number, Gram molecular weight, W, =, ×N, MW, =, , •฀ No.฀of฀atoms฀present฀in฀a฀given฀element฀, =, , Weight, × Avogadro number, Gram molecular weight, , 6.022฀×฀1023฀molecules.฀, , •฀ The฀number฀of฀atoms฀in฀one฀gram฀atom฀of฀an฀element฀, or฀฀the฀number฀of฀molecules฀present฀in฀one฀gram฀mole฀, of฀substance,฀i.e.,฀6.022฀×฀1023฀is฀known฀as฀Avogadro’s, number or฀Avogadro’s฀constant denoted฀by฀N., , •฀ The฀mass฀of฀1฀mole฀of฀a฀substance฀in฀grams฀is฀known฀, , •฀, , as฀molar mass., Gram฀ molecular฀ weight฀ =฀ weight฀ of฀ molecule฀ in฀฀, g฀×฀6.022฀×฀1023., Wt.฀of฀one฀molecule฀in฀grams฀, Molecular Wt., Molecular Wt., =, =, N, 6.022 × 10 23, Wt.฀of฀one฀atom฀in฀grams, =, , Atomic weight, Atomic weight, =, N, 6.023 × 10 23, , •฀ The฀gaseous฀substances฀at฀NTP฀will฀have฀6.022฀×฀1023฀, molecules฀in฀22.4฀litres฀or฀22400฀cc฀whose฀weight฀is฀, equal฀to฀their฀molecular฀weight.฀, , Objective Questions, 26. One฀mole฀of฀CO2฀contains, (1)฀ 6.02฀×฀1023฀atoms฀of฀C, (2)฀ 6.02฀×฀1023฀atoms฀of฀O, (3)฀ 18.1฀×฀1023฀atoms฀of฀CO2, (4)฀ 3฀grams฀of฀carbon, 27. How฀many฀water฀molecules฀will฀be฀lost฀on฀dehydrating฀, 0.684฀g฀of฀sucrose?, (1)฀ 1.3244฀×฀1022, (2)฀ 6.622฀×฀1021, (3)฀ 6.02฀×฀1020, (4)฀ 7.224฀×฀1021, 28. Which฀ one฀ of฀ the฀ following฀ gas฀ contains฀ the฀ same฀, number฀of฀molecules฀as฀16฀g฀of฀oxygen?฀, (1)฀ 16฀g฀of฀O3฀, ฀, (2)฀ 16฀g฀of฀SO2, (3)฀ 32฀g฀of฀SO2฀, ฀, (4)฀ All฀the฀above

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1.6, , Objective Chemistry - Vol. I, , 29. 18฀g฀of฀water฀contains, (1)฀ 1฀g฀atom฀of฀hydrogen฀atom, (2)฀ 2฀g฀atom฀of฀hydrogen฀atom, (3)฀ 3฀g฀atom฀of฀hydrogen฀atom, (4)฀ None฀of฀these, 30. Volume฀at฀NTP฀of฀0.44฀g฀of฀CO2฀is฀the฀same฀as฀that฀of฀, (1)฀ 0.02฀g฀of฀H2฀, (2)฀ 0.085฀g฀of฀NH3฀, (3)฀ 320฀mg฀of฀gaseous฀SO2, (4)฀ All฀the฀above฀, 31. 4.4฀g฀of฀an฀unknown฀gas฀occupies฀2.24฀litres฀of฀volume฀, at฀STP.฀The฀gas฀may฀be, (1)฀ carbon฀dioxide฀ (2)฀ carbon฀monoxide, (3)฀ oxygen฀ ฀, (4)฀ sulphur฀dioxide, 32. Which฀ of฀ the฀ following฀ has฀ the฀ smallest฀ number฀ of฀, molecules?, (1)฀ 0.1฀mole฀of฀CO2฀gas, (2)฀ 11.2฀litres฀of฀CO2฀gas, (3)฀ 22฀g฀of฀CO2฀gas, (4)฀ 22.4฀×฀103฀ml฀of฀CO2฀gas, 33. Choose฀the฀wrong฀statement.฀, (1)฀ 1฀mole฀means฀6.023฀×฀1023฀particles, (2)฀ Molar฀mass฀is฀mass฀of฀1฀molecule, (3)฀ Mole฀is฀mass฀of฀1฀mole฀of฀substance, (4)฀ ฀Molar฀ mass฀ is฀ molecular฀ mass฀ expressed฀ in฀, grams, 34. Which฀of฀the฀following฀pairs฀contain฀equal฀number฀of฀, atoms?฀, (1)฀ 11.2฀cc฀of฀the฀N2฀and฀0.015฀g฀of฀nitric฀oxide, (2)฀ ฀22.4฀litres฀of฀nitrous฀oxide฀and฀22.4฀litres฀of฀nitric฀, oxide, (3)฀ 1฀milli฀mole฀of฀HCl฀and฀and฀0.5฀milli฀mole฀of฀H2S, (4)฀ 1฀mole฀of฀H2O2฀and฀1฀mole฀of฀N2O4, 35. A฀piece฀of฀copper฀weighs฀0.635฀g.฀How฀many฀atoms฀of฀, copper฀does฀it฀contain?, (1)฀ 6.02฀×฀1022฀electrons, (2)฀ 6.02฀×฀1021฀electrons, (3)฀ 6.023฀×฀1023฀electrons, (4)฀ 6.012฀×฀1024฀electrons, 36. How฀many฀electrons฀are฀present฀in฀1.6฀g฀of฀methane?, (1)฀ 6.02฀×฀1023฀electrons, (2)฀ 6.02฀×฀1022฀electrons, (3)฀ 6.02฀×฀1024฀electrons, (4)฀ 6.02฀×฀1025฀electrons, 37. How฀many฀years฀would฀it฀take฀to฀spend฀one฀Avogadro฀, number฀ of฀ rupees฀ at฀ a฀ rate฀ of฀ 10฀ lakh฀ of฀ rupees฀ per฀, second?฀, , (1)฀, (2)฀, (3)฀, (4)฀, , 19.089฀×฀109฀years, 18.089฀×฀109฀years, 19.089฀×฀1010฀years, 19.089฀×฀1011฀years฀, , 38. 4.6฀ ×฀ 1022฀ atoms฀ of฀ an฀ element฀ weigh฀ 13.8฀ g.฀ The฀, atomic฀mass฀of฀the฀element฀is, (1)฀ 290฀ ฀ (2)฀ 180฀ ฀ (3)฀ 13.4฀฀ ฀ (4)฀ 10.4, 39. The฀number฀of฀moles฀of฀SO2Cl2฀in฀13.5฀g฀is, (1)฀ 0.1฀ ฀ (2)฀ 0.2฀ ฀ (3)฀ 0.3฀ ฀ (4)฀ 0.4, 40. The฀ total฀ number฀ of฀ protons฀ in฀ 10฀ g฀ of฀ calcium฀, ฀carbonate฀is฀, (1)฀ 3.0115฀×฀1024, (2)฀ 1.5057฀×฀1024, (3)฀ 2.0478฀×฀1024, (4)฀ 4.0956฀×฀1024, 41. Which฀of฀the฀following฀is฀wrong?฀, (1)฀ ฀One฀mole฀of฀hydrogen฀weighs฀less฀than฀one฀mole฀, of฀glucose, (2)฀ ฀Two฀moles฀of฀hydrogen฀and฀one฀mole฀of฀helium฀, weigh฀the฀same, (3)฀ ฀0.1฀mole฀of฀oxygen฀weighs฀more฀than฀one฀mole฀of฀, hydrogen, (4)฀ ฀One฀mole฀of฀nitrogen฀and฀half฀a฀mole฀of฀oxygen฀, weigh฀the฀same, 42. Avogadro’s฀law฀finds฀application฀in฀the฀determination฀of฀, (1)฀ Atomicity฀of฀gases, (2)฀ Molecular฀weight฀of฀gases, (3)฀ Molecular฀formula฀of฀certain฀gaseous฀compounds฀, (4)฀ All฀the฀above, 43. Assuming฀ the฀ density฀ of฀ water฀ is฀ 1g/ml,฀ the฀ volume฀, occupied฀by฀one฀molecule฀of฀water฀is฀, (1)฀ 3฀×฀10–23฀cc฀, (2)฀ 1.5฀×฀10–23฀cc, –23, (3)฀ 6฀×฀10 ฀cc฀, (4)฀ 3฀×฀10–฀22฀cc, 44. Molecular฀weight฀of฀haemoglobin฀is฀67200.฀If฀haemo­, globin฀ contains฀ 0.33%฀ of฀ iron฀ atoms,฀ the฀ number฀ of฀, iron฀atoms฀that฀are฀present฀in฀one฀molecule฀of฀haemo­, globin฀is฀(At.฀wt.฀of฀iron฀=฀56), (1)฀ 2฀ ฀ (2)฀ 4฀ ฀ (3)฀ 6฀ ฀ (4)฀ 8, 45. How฀many฀moles฀of฀atoms฀are฀present฀in฀one฀mole฀of฀, CH3COOH฀molecule?฀, (1)฀ ฀2฀moles฀of฀C฀atoms,฀4฀moles฀of฀H฀atoms,฀2฀moles฀, of฀O฀atoms, (2)฀ ฀1฀mole฀of฀C฀atoms,฀2฀moles฀of฀H฀atoms,฀1฀mole฀of฀, O฀atoms, (3)฀ ฀2฀moles฀of฀C฀atoms,฀3฀moles฀of฀H฀atoms,฀2฀moles฀, of฀O฀atoms฀, (4)฀ None

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Basic Concepts of Chemistry 1.7, , 46. Which฀contains฀the฀greatest฀number฀of฀oxygen฀atoms?, (1)฀ 1฀g฀of฀O2, (2)฀ 1฀g฀of฀O2, (3)฀ 1฀g฀of฀O3, (4)฀ All฀have฀the฀same฀number฀of฀atoms, 47. Which฀of฀the฀following฀pairs฀of฀gases฀contain฀the฀same฀, number฀of฀molecules?, (1)฀ 16฀g฀of฀O2,฀14฀g฀of฀N2, (2)฀ 8฀g฀of฀O2,฀22฀g฀of฀CO2, (3)฀ 28฀g฀of฀N2,฀22฀g฀of฀CO2, (4)฀ 32฀g฀of฀O2,฀32฀g฀of฀N2, 48. A฀glass฀of฀juice฀contains฀9฀g฀of฀glucose.฀The฀number฀of฀, carbon฀atoms฀in฀the฀glass฀of฀juice฀is฀, (1)฀ 1.8069฀×฀1023฀, (2)฀ 1.5012฀×฀1023, 23฀, (3)฀ 2.5012฀×฀10, (4)฀ None, 49. Weight฀of฀6.023฀×฀1021฀atoms฀of฀zinc฀(At.฀wt.฀of฀Zn฀=฀, 65.4)฀is฀, (1)฀ 0.645฀g฀ ฀, (2)฀ 0.0654฀g, (3)฀ 6.54฀g฀ ฀, (4)฀ 0.00654฀g, 50. The฀ number฀ of฀ ions฀ produced฀ by฀ 0.1฀ mole฀ of฀฀, AlCl3฀.฀6H2O฀in฀a฀litre฀solution฀is฀, (1)฀ 5฀×฀6023฀×฀1022฀ ฀, (2)฀ 4฀×฀6.023฀×฀1023, –22฀, (3)฀ 4฀×฀6.023฀×฀10 ฀, (4)฀ 4฀×฀6.023฀×฀1022, 51. Two฀containers฀have฀equal฀weights฀of฀NO2฀and฀N2O.฀, The฀one฀containing฀more฀number฀of฀moles฀is, (1)฀ NO2, (2)฀ N2O฀, (3)฀ both฀have฀same฀number฀of฀moles฀, (4)฀ cannot฀be฀determined฀, 52. Which฀of฀the฀following฀mixtures฀contain฀less฀number฀, of฀ions?, (1)฀ 2M฀K2SO4;฀3M฀Na2CO3, (2)฀ 2M฀NaCl;฀2M฀KCl, (3)฀ 2M฀MnSO4;฀2M฀K2SO4, (4)฀ 2M฀K2SO4;฀2M฀(NH4)2SO4, , answers, (26)฀ 1฀, (31)฀ 1฀, (36)฀ 1฀, (41)฀ 4฀, (46)฀ 4฀, (51)฀ 2฀, , 55. The฀number฀of฀gram฀atoms฀of฀sulphur฀that฀represents฀, 0.5฀mole฀of฀sulphuric฀acid฀is, (1)฀ 0.2฀ ฀ ฀ (2)฀ 0.4฀ ฀ ฀ (3)฀ 0.5฀ ฀ ฀ (4)฀ 0.9, , (28)฀ 3฀, (33)฀ 2฀, (38)฀ 2฀, (43)฀ 1฀, (48)฀ 1฀, (53)฀ 2฀, , (29)฀ 2฀, (34)฀ 1฀, (39)฀ 1฀, (44)฀ 2฀, (49)฀ 1฀, (54)฀ 1฀, , (30)฀ 1, (35)฀ 2, (40)฀ 1, (45)฀ 1, (50)฀ 4, (55)฀ 3฀, , CaLCULatIon oF eMpIRICaL FoRMULa, anD MoLeCULaR FoRMULa, , •฀ Empirical formula of฀a฀compound฀gives฀the฀simplest฀, •฀, •฀, ฀, ฀, ฀, ฀, ฀, , •฀, •฀, , 53. Caffeine฀ (molecular฀ weight฀ =฀ 194)฀ contains฀ 28.9%฀, nitrogen.฀ The฀ number฀ of฀ nitrogen฀ atoms฀ in฀ caffeine฀, molecule฀is฀, (1)฀ 2฀ ฀ ฀ (2)฀ 4฀ ฀ ฀ (3)฀ 7฀ ฀ ฀ (4)฀ 8, 54. Sugar฀costs฀Rs.฀10/kg.฀The฀cost฀of฀one฀mole฀of฀sugar฀is฀, (1)฀ Rs.฀3฀ps฀42฀, (2)฀ Rs.฀6฀ps฀84, (3)฀ Rs.฀1฀ps฀80฀, (4)฀ None, , (27)฀ 1฀, (32)฀ 1฀, (37)฀ 1฀, (42)฀ 4฀, (47)฀ 1฀, (52)฀ 2฀, , ratio฀of฀the฀number฀of฀atoms฀of฀different฀elements฀pre­, sent฀in฀one฀molecule฀of฀a฀compound.฀, Empirical฀formula฀will฀not฀give฀the฀actual฀number฀of฀, atoms฀of฀different฀elements฀present฀in฀one฀molecule฀of฀, the฀compound.฀, Calculation฀ of฀ the฀ empirical฀ formula฀ involves฀ the฀, ฀following฀steps.฀, 1.฀ ฀Percentage฀composition฀by฀weight฀of฀each฀฀element฀, in฀the฀compound฀should฀be฀determined.฀, 2.฀ ฀The฀percentage฀of฀each฀element฀should฀be฀divided฀, by฀its฀atomic฀weight฀to฀get฀the฀relative฀number฀of฀, atoms฀of฀each฀element.฀, 3.฀ ฀The฀numbers฀obtained฀in฀the฀above฀step฀(2)฀ should฀, be฀divided฀to฀get฀the฀simplest฀ratio.฀, 4.฀ I฀ f฀the฀numbers฀obtained฀in฀the฀above฀step฀(3)฀ are฀, not฀whole฀numbers;฀for,฀they฀should฀be฀multiplied฀, by฀a฀suitable฀integer฀to฀get฀the฀whole฀number฀ratio.฀, 5.฀ ฀The฀ratio฀obtained฀in฀the฀above฀step฀(4)฀ gives฀the฀, empirical฀formula.฀, Molecular formula represents฀ the฀ actual฀ number฀ of฀, atoms฀of฀different฀elements฀present฀in฀one฀molecule฀of฀, the฀compound.฀, For฀ certain฀ compounds,฀ the฀ empirical฀ formulae฀ and฀, molecular฀formula฀may฀be฀same.฀, Molecular฀formula฀=฀Empirical฀formula฀×฀n, n=, , Molecular weight, Empirical formula weight, , •฀ Molecular฀weight฀of฀a฀substance฀can฀be฀determined฀by฀, , •฀, , different฀ methods฀ such฀ as฀ (i)฀ vapour฀ density฀ method฀, and฀(ii)฀methods฀based฀on฀colligative฀properties.฀, 2฀×฀vapour฀density฀=฀Molecular฀weight฀, The฀ molecular฀ weights฀ of฀ volatile฀ compounds฀ are฀, ฀determined฀by฀Victor฀Mayer’s฀method.฀

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1.8, , Objective Chemistry - Vol. I, , StoIChIoMetRy anD StoIChIoMetRIC, CaLCULatIonS, , Objective Questions, 56. The฀ vapour฀ density฀ of฀ gas฀A฀ is฀ four฀ times฀ that฀ of฀ B.฀, If฀ the฀ molecular฀ mass฀ of฀ B฀ is฀ M฀ then฀ the฀ molecular฀, mass฀of฀A฀is฀, (1)฀ M฀ ฀ (2)฀ 2M฀ ฀ (3)฀ M/4฀ ฀ (4)฀ 4M, , •฀ Stoichiometric฀ calculations฀ help฀ in฀ calculating฀, , 57. Vapour฀density฀of฀a฀volatile฀substance฀is฀4฀(CH4฀=฀1).฀, Its฀molecular฀weight฀would฀be฀, (1)฀ 8฀ ฀ (2)฀ 2฀ ฀ (3)฀ 64฀ ฀ (4)฀ 128, , ฀, ฀, ฀, ฀, , 58. An฀oxide฀of฀metal฀(M)฀has฀40%฀by฀mass฀of฀oxygen.฀, Metal฀M฀has฀a฀relative฀atomic฀mass฀of฀24.฀The฀empiri­, cal฀formula฀of฀oxide฀is฀, (1)฀ M2O฀ ฀ (2)฀ M2O3฀ ฀ (3)฀ MO฀ ฀ (4)฀ M3O4, 59. A฀compound฀(60฀g)฀on฀analysis฀gave฀C฀=฀24฀g,฀H฀=฀4฀g,฀, O฀=฀32฀g.฀Its฀empirical฀formula฀is, (1)฀ C2H4O2฀ ฀, (2)฀ C2H2O2, (3)฀ CH2O2฀ ฀, (4)฀ CH2O, 60. A฀compound฀contains฀38.8%฀C,฀16.0%฀H฀and฀45.2% N.฀, The฀formula฀of฀the฀compound฀would฀be, (1)฀ CH3NH2฀฀, (2)฀ CH3CN, (3)฀ C2H5CN฀฀, (4)฀ CH2฀(NH2)2, 61. An฀organic฀compound฀on฀analysis฀was฀found฀to฀con­, tain฀0.032%฀sulphur.฀The฀molecular฀mass฀of฀the฀com­, pound,฀if฀its฀molecule฀contains฀two฀sulphur฀atoms฀is฀, (1)฀ 200฀, ฀, (2)฀ 2000฀, (3)฀ 20,000฀ ฀, (4)฀ 2,00,000, 62. 15฀ ml฀ of฀ a฀ gaseous฀ hydrocarbon฀ requires฀ 45฀ ml฀ of฀, oxygen฀for฀complete฀combustion฀and฀30฀ml฀of฀CO2฀is฀, formed.฀The฀formula฀of฀the฀hydrocarbon฀is฀, (1)฀ C3H6฀ ฀ (2)฀ C2H6฀ ฀ (3)฀ C4H10฀ ฀ (4)฀ C2H4, 63. Insulin฀ contains฀ 3.4%฀ of฀ sulphur.฀ The฀ minimum฀, ฀molecular฀mass฀of฀insulin฀is฀, (1)฀ 940฀ ฀ (2)฀ 560฀ ฀ (3)฀ 470฀ ฀ (4)฀ 350, 64. The฀concentration฀of฀C฀=฀85.45%฀and฀H฀=฀14.55%฀is฀, not฀obeyed฀by฀the฀formula, (1)฀ CH2฀ ฀ (2)฀ C2H4฀ ฀ (3)฀ C2H6฀ ฀ (4)฀ C4H8, , •฀, , •฀, , •฀, ฀, ฀, ฀, , •฀, , MethoDS FoR expReSSIng the, ConCentRatIon oF SoLUtIonS, Mass per cent, , •, , •฀, , (56)฀ 4฀, (61)฀ 4฀, , (57)฀ 3฀, (62)฀ 4฀, , (58)฀ 3฀, (63)฀ 1฀, , •฀, •฀, , answers, (59)฀ 4฀, (64)฀ 3฀, , (60)฀ 1, (65)฀ 4, , Mass฀per฀cent฀=฀, , Mass of solute, × 100, Mass of solution, , •฀ Mole fraction is฀the฀ratio฀of฀the฀number฀of฀moles฀of฀, , –1, , 65. The฀ density฀ of฀ air฀ is฀ 0.001293฀ gm฀ L .฀ Its฀ vapour฀, density฀is, (1)฀ 143฀ ฀ (2)฀ 14.3฀ ฀ ฀(3)฀ 1.43฀ ฀ (4)฀ 0.143, , ฀whether฀ the฀ production฀ of฀ a฀ particular฀ substance฀ is฀, e฀ conomically฀cheap฀or฀not.฀, Stoichiometric฀calculations฀are฀of฀four฀types:, ฀ ฀(i)฀ ฀Calculations฀based฀on฀weight–weight฀relationships, ฀ (ii)฀ ฀Calculations฀based฀on฀weight–volume฀relationships฀, ฀(iii)฀ ฀Calculations฀based฀on฀volume–volume฀relationships, ฀(iv)฀ ฀Calculations฀ based฀ on฀ weight–volume–energy฀, ฀relationships฀, If฀ the฀ amount฀ of฀ reactant฀ in฀ a฀ particular฀ reaction฀ is฀, known,฀ then฀ the฀ amount฀ of฀ the฀ other฀ substance฀ re­, quired฀ in฀ the฀ reaction฀ or฀ the฀ amount฀ of฀ the฀ product฀, formed฀in฀the฀reaction฀can฀be฀calculated.฀, For฀ stoichiometric฀ calculations,฀ the฀ following฀ steps฀, should฀be฀considered.฀, (a)฀ ฀a฀balanced฀chemical฀equation฀using฀chemical฀for­, mulae฀of฀reactants฀and฀products฀must฀be฀written.฀, (b)฀ ฀The฀coefficients฀of฀a฀balanced฀chemical฀equation฀, give฀the฀mole฀ratio฀of฀the฀reactants฀and฀products.฀, (c)฀ ฀The฀ mole฀ ratio฀ can฀ be฀ converted฀ into฀ weight­, weight฀ ratio,฀ weight­volume฀ ratio฀ or฀ volume­฀, volume฀ratio.฀, Limiting reactant or limiting reagent is฀the฀reactant฀, that฀is฀entirely฀consumed฀when฀a฀reaction฀proceeds฀to฀, completion.฀The฀ reactant฀ that฀ is฀ not฀ completely฀ con­, sumed฀in฀a฀reaction฀is฀called฀as฀an฀excess reactant., , one฀ component฀ to฀ the฀ total฀ number฀ of฀ moles฀ (solute฀, and฀solvent)฀in฀a฀binary฀solution.฀, n2, Mole฀fraction฀of฀solute฀χA฀=฀, n1 + n2, ฀where฀n1฀and฀n2฀are฀the฀number฀of฀moles฀of฀solvent฀and฀, solute,฀respectively.฀, W, The฀number฀of฀moles฀of฀a฀substance฀=฀, M, Mole฀fraction฀of฀a฀substance฀A฀in฀a฀solvent฀B฀is฀given฀by, WA, MA, χA฀=฀, WA, W, + B, MA, MB

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Basic Concepts of Chemistry 1.9, , •฀ For฀a฀dilute฀solution,฀the฀number฀of฀moles฀of฀a฀solute฀, , •฀ Number฀ of฀ moles฀ present฀ in฀ a฀ solution฀ =฀ Molarity฀ ×฀, Vol.฀in฀litres.฀, , in฀the฀denominator฀can฀be฀neglected.฀Then฀, χA฀=฀, , •฀ Number฀ of฀ milli฀ moles฀ present฀ in฀ a฀ solution฀ =฀, , WA, M, × B, M A WB, , •฀ In฀a฀solution,฀the฀sum฀of฀mole฀fractions฀of฀all฀compo­, , •฀, , nents฀=฀1.฀, , Molarity, , •฀ Molarity:฀M฀is฀the฀number฀of฀moles฀of฀a฀solute฀pre­, sent฀in฀one฀litre฀of฀a฀solution.฀, Molarity฀is฀represented฀by฀M.฀, M฀=฀, M฀=฀, or฀M฀=฀, M฀=฀, , Number of moles of solute, Volume of solution in litres, , •฀, •฀, , normality, , •฀ Normality฀is฀the฀number฀of฀gram฀equivalents฀of฀a฀sol­, ute฀present฀in฀one฀litre฀of฀a฀solution.฀It฀is฀denoted฀by฀N., , Weight of the solute (W ), Molecular ( MW ) × volume in litres (V ), , Normality N =, , W, M .W . × V in lit, , N=, , W × 1000, M .W . × V in cc, , •฀ If฀one฀gram฀molecular฀weight฀of฀the฀substance฀is฀present฀, •฀, •฀, , •฀, , in฀one฀litre฀of฀the฀solution฀it฀is฀said฀to฀be฀1M฀(one฀molar).฀, If฀0.1฀g฀molecular฀weight฀of฀the฀substance฀is฀present฀, in฀ one฀ litre฀ of฀ the฀ solution,฀ it฀ is฀ said฀ to฀ be฀ 0.1M฀ or฀, decimolar฀or฀M/10฀of฀the฀solution.฀, Weight฀ of฀ the฀ substance฀ present฀ in฀ one฀ litre฀ =฀, Molarity฀× Mol.฀wt.฀If฀the฀solution฀of฀M1฀of฀volume฀V1฀, is฀diluted฀to฀valency฀V2,฀its฀molarity฀M2฀can฀be฀calcu­, lated฀by฀V1M1฀=฀V2M2., The฀volume฀to฀be฀added฀to฀dilute฀a฀solution฀of฀volume฀, V1฀of฀molarity฀M1฀to฀a฀concentration฀of฀M2฀is฀given฀by฀, volume฀of฀water฀to฀be฀added฀=฀, Volume฀after฀dilution฀–฀Volume฀before฀dilution฀or฀V2฀–฀V1, Volume฀of฀water฀to฀be฀added฀=฀, , V1 M1, − V1, M2, , •฀ When฀ the฀solutions฀ of฀two฀different฀ substances฀react฀, together,฀then฀, , ฀, •฀, , Molarity฀×฀Vol.฀in฀cc.฀, Molarity฀of฀a฀mixture฀of฀solutions฀of฀different฀concen­, trations฀of฀the฀same฀substance฀can฀be฀calculated฀by฀, V M + V M + ...... + Vn M n, M฀=฀ 1 1 2 2, Total Volume, Molarity฀is฀temperature฀dependent.฀, Units฀of฀molarity฀are฀moles฀litre–1, , V1 M1, V M, = 2 2, n1, n2, , where฀V,฀M฀and฀n฀are฀volume,฀molarity฀and฀number฀of฀, molecules฀participating฀in฀the฀reaction฀of฀a฀substance,฀, respectively.฀, If฀density฀(d)฀and฀per฀cent฀by฀weight฀of฀a฀substance฀in฀, a฀solution฀are฀known,฀then฀its฀molarity, M฀=฀d฀×฀per฀cent฀×฀, , 10, M.W., , Number of gram equivalents of solute, Volume of solution in litres, , Weight of the solute (W ), Equivalent weight ( EW ) × volume in litres (V ), , or฀N฀=฀, , W, EW × V in litres, , or฀N฀=฀, , W × 1000, EW × V in cc, , •฀ If฀ one฀ gram฀ equivalent฀ weight฀ of฀ a฀ substance฀ is฀ pre­, •฀, •฀, , sent฀in฀one฀litre฀of฀a฀solution,฀it฀is฀said฀to฀be฀1฀N฀(one฀, normal).฀, If฀0.1฀gram฀equivalent฀weight฀of฀a฀substance฀is฀present฀, in฀one฀litre฀of฀a฀solution,฀it฀is฀said฀to฀be฀0.1฀N฀or฀deci­, normal฀or฀N/10฀of฀the฀solution.฀, Weight฀ of฀ the฀ substance฀ present฀ in฀ one฀ litre฀ =฀, Normality฀×฀Equivalent฀weight., W฀=฀VNE, , •฀ If฀the฀solution฀of฀N1฀of฀volume฀V1฀is฀diluted฀to฀a฀vol­, ume฀V2฀then฀its฀normality฀N2฀can฀be฀calculated฀by, V1N1฀=฀V2N2, , •฀ The฀volume฀of฀water฀to฀be฀added฀=฀, ฀ Volume฀ after฀ dilution฀ –฀ Volume฀ before฀ dilution฀ or฀, ฀, , V2฀–฀V1.฀, VN, Volume฀of฀water฀to฀be฀added฀=฀ 1 1 −฀V1, N2, , •฀ When฀ the฀solutions฀ of฀two฀different฀ substances฀react฀, with฀ each฀ other,฀ then฀ V1N1฀ =฀ V2N2฀ where฀ V1฀ and฀ N1฀, are฀the฀volume฀and฀normality฀of฀one฀substance฀while฀, V2฀ and฀ N2฀ are฀ volume฀ and฀ normality฀ of฀ the฀ other฀, substance.฀

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1.10 Objective Chemistry - Vol. I, , •฀ The฀ weight฀ of฀ a฀ substance฀ that฀ can฀ react฀ with฀ a฀ par­, , •฀, ฀, •฀, , •฀, , ticular฀volume฀(V)฀of฀a฀solution฀of฀another฀substance฀, having฀normality฀(N)฀and฀equivalent฀weight฀(E)฀can฀be฀, calculated฀by, W฀=฀VNE, If฀the฀density฀(d)฀and฀per฀cent฀by฀weight฀of฀a฀substance฀, in฀ a฀ solution฀ are฀ known,฀ then฀ its฀ normality฀ can฀ be฀฀, calculated฀by, 10, N฀=฀d฀×฀per฀cent฀×, EW, Number฀ of฀ gram฀ equivalents฀ present฀ in฀ solution฀ =฀, Normality฀×฀Volume฀in฀litres฀(N฀×฀V฀in฀litres).฀Number฀, of฀milli฀equivalents฀present฀in฀a฀solution฀=฀Normality฀×฀, Volume฀in฀CC฀(N฀×฀V฀in฀CC)., Normality฀of฀a฀mixture฀of฀solutions฀of฀different฀con­, centrations฀of฀the฀same฀substance฀, N฀=฀, , Equivalent฀weight฀of฀base฀=฀, Molecular weight or formula weight of the base, Acidity of the base, , •฀ Acidity฀of฀a฀base฀is฀the฀number฀of฀replaceable฀hydrox­, yl฀(–OH)฀groups฀in฀the฀molecule฀of฀a฀base.฀, Formula weight of NaOH, E.฀Wt.฀for฀NaOH฀=฀, 1, Formula weight of KOH, E.฀Wt.฀for฀KOH฀=฀, 1, , •฀, , V1 N1 + V2 N 2 + ........... + Vn N n, Total volume, , •฀ In฀acid–base฀neutralisation฀reactions,฀the฀excess฀sub­, stance฀is฀given฀by฀, V N −V N, N฀=฀ 1 1 2 2, Total Volume, , •฀ Relation฀ between฀ molarity฀ (M)฀ and฀ normality฀ (N)฀ of฀, any฀solution฀is฀, ฀, , Molarity฀×฀, , Molecular weight, ฀=฀normality฀, Equivalent weight, , ฀, , Molarity฀=฀, , Normality × Equivalent weight, Molecular weight, , equivalent Weights, , •฀ For acids: Equivalent฀weight฀of฀an฀acid฀=฀, ฀, , •฀ For bases, , Molecular weight or formula weight of the acid, Basicity of the acid, , •฀ Basicity฀of฀an฀acid฀is฀the฀number฀of฀replaceable฀hydro­, gen฀(by฀metal฀ions)฀in฀a฀molecule฀of฀the฀acid.฀, E.฀Wt.฀for฀HCl฀=฀, , Formula weight of HCl, 1, , E.฀Wt.฀for฀Ba(OH)2฀=฀, ฀, For Salts, Equivalent฀weight฀, =, , Formula weight of Ba ( OH )2, 2, , Formula weight of the salt, Total charge on the cation or the anion of thhe salt, , •฀ For oxidants and reductants, Equivalent฀weight฀, =, , Formula weight, Number of electrons transfered in the reaction per moole, , •฀ Equivalent฀weight฀of฀certain฀compounds.฀, Substance, Acids, HCl, HNO3, H2SO4, C2H2O4฀.฀2H2O, H3PO4, Bases, NaOH, KOH, Ba(OH)2, Fe(OH)3, Salts, NaCl, Na2CO3, AgNO3, Oxidants, KMnO4, K2Cr2O7, , Equivalent weight in g, 36.5, 63, 49, 63฀(oxalic฀acid), 32.7, 40, 56, 85.67, 35.7, 58.5, 53, 170, , E.฀Wt.฀for฀HNO3฀=฀, , Formula weight of HNO3, 1, , ฀, , E.฀Wt.฀for฀H2SO4฀=฀, , Formula weight of H 2SO 4, 2, , •฀ Molality is฀the฀number฀of฀moles฀of฀a฀solute฀present฀in฀, , ฀, , Formula weight of H 3 PO 4, E.฀Wt.฀for฀H3PO4฀=฀, 3, , 1฀kg฀(100฀g)฀of฀a฀solvent.฀, Molality฀is฀represented฀by฀“m”.฀Its฀units฀are฀mole฀kg–1., , •฀, , 31.6฀(acid฀medium), 49฀(acid฀medium)

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Basic Concepts of Chemistry 1.11, , •฀ Molality฀=฀, ฀, , •฀, •฀, , or฀m฀=฀, , Number of moles of solute, Weight of solvent in kg, W, MW × Wt of solvent in kg, , W × 1000, ฀, or฀m฀=฀, MW × Wt of solvent in gram, Temperature฀ has฀ no฀ effect฀ on฀ molality฀ and฀ mole฀, ฀fractions฀since฀the฀quantities฀of฀solute฀and฀solvent฀are฀, ฀expressed฀by฀weights.฀, Molarity฀ and฀ normality฀ changes฀ with฀ temperature฀, since฀the฀volume฀of฀solvent฀changes฀with฀temperature.฀, , Objective Questions, 66. In฀a฀clinical฀laboratory,฀a฀sample฀of฀urine฀containing฀, 0.120฀g฀of฀urea฀NH2CONH2฀(M.฀Wt.฀60)฀was฀treated฀, with฀excess฀of฀nitrous฀acid.฀The฀urea฀reacted฀according฀, to฀the฀following฀equation, NH2CONH2฀+ 2HNO2 , → CO2 + 2N2 + 3H2O, ฀ The฀gas฀formed฀was฀passed฀through฀aqueous฀sodium฀, hydroxide฀and฀final฀volume฀is฀measured฀at฀STP.฀What฀, was฀the฀volume?฀, (1)฀ 89.6฀cc฀ ฀, ฀, (2)฀ 179.2฀cc, (3)฀ 44.8฀cc฀ ฀, ฀, (4)฀ 22.4฀cc, 67. How฀many฀grams฀of฀water฀are฀produced฀by฀the฀com­, plete฀combustion฀of฀1.00฀litre฀at฀STP฀of฀methane?, 1.00, ×2฀, 22.4, 1.00, (3)฀, × 18 ฀, 2.24 × 2, (1)฀, , ฀, ฀, , 1.00, × 2 × 18, 22.4, 1.00 × 2, (4)฀, 22.4 × 18, (2)฀, , 68. The฀weight฀of฀Na2CO3฀that฀would฀be฀needed฀to฀react฀, with฀0.1฀mole฀of฀HCl฀according฀to฀the฀equation฀is, → 2NaCl + H2O + CO2, Na2CO3 + 2HCl , (1)฀ 5.3฀g฀ ฀, (2)฀ 53฀g, (3)฀ 0.53฀g฀ ฀, (4)฀ 0.053฀g, 69. The฀ amount฀ of฀ silver฀ chloride฀ formed฀ on฀ mixing฀฀, 250฀ml฀of฀0.1M฀AgNO3฀with฀400฀ml฀of฀0.1M฀NaCl฀is, (1)฀ 0.10M฀ ฀, (2)฀ 0.05M, (3)฀ 0.025M฀ ฀, (4)฀ 0.2M, 70. How฀ much฀ of฀ 0.1M฀ of฀ HCl฀ must฀ be฀ added฀ to฀฀, 0.55฀ litre฀ of฀ 0.1M฀ Na2CO3฀ if฀ all฀ of฀ this฀ is฀ to฀ be฀, ฀converted฀to฀CO2?, (1)฀ 0.55฀litre฀, ฀, (2)฀ 1.1฀litre, (3)฀ 0.275฀litre฀, ฀, (4)฀ 100฀ml, , 71. 1.0฀g฀of฀pure฀calcium฀carbonate฀was฀found฀to฀react฀with฀, 50฀ ml฀ of฀ dilute฀ HCl฀ for฀ completion฀ of฀ the฀ ฀reaction.฀฀, The฀strength฀of฀the฀HCl฀solution฀is฀, (1)฀ 4M฀ ฀ (2)฀ 2M฀ ฀ (3)฀ 0.4M฀ ฀ (4)฀ 0.2M, 72. 12฀g฀of฀magnesium฀(At.฀Wt.฀=฀24)฀will฀react฀complete­, ly฀with฀an฀acid฀to฀give, (1)฀ one฀mole฀of฀H2฀ (2)฀ one­half฀mole฀of฀H2, (3)฀ one฀mole฀of฀O2฀ (4)฀ none฀of฀these, 73. What฀volume฀of฀CO2฀measured฀at฀STP฀can฀be฀obtained฀, by฀reacting฀50฀g฀of฀CaCO3฀with฀excess฀hydrochloric฀acid?, → ฀CaCl2฀+฀H2O฀+฀CO2, CaCO3฀+฀2HCl฀ , (1)฀ 22.4฀litres฀, (3)฀ 1.12฀litres฀, , (2)฀ 11.2฀litres, (4)฀ 44.8฀litres, , 74. In฀the฀hydrogenation฀of฀phenyl฀ethylene฀C6H5CH฀=฀CH2฀, using฀ a฀ platinum฀ catalyst฀ the฀ volume฀ of฀ hydrogen฀, (measured฀at฀STP)฀that฀reacts฀with฀one฀mole฀of฀phenyl฀, ethylene฀could฀be, (1)฀ 11.2฀litres฀, (2)฀ 22.4฀litres, (3)฀ 44.8฀litres฀, (4)฀ 1฀litre, 75. What฀ is฀ the฀ volume฀ of฀ oxygen฀ required฀ for฀ complete฀, combustion฀of฀a฀mixture฀of฀5฀cc฀of฀CH4฀and฀5฀cc฀of฀C2H4?, (1)฀ 25฀cc฀฀ ฀ (2)฀ 5฀cc฀ ฀ (3)฀ 50฀cc฀ ฀ (4)฀ 10฀cc, 76. A฀ certain฀ sample฀ of฀ coal฀ contains฀ 1%฀ sulphur฀ by฀, weight.฀ What฀ is฀ the฀ weight฀ of฀ sulphur฀ dioxide฀ pro­, duced฀when฀2฀×฀106฀kg฀of฀this฀coal฀is฀burnt?, (1)฀ 2฀×฀104฀kg฀, (2)฀ 4฀×฀104฀kg, 5, (3)฀ 4฀×฀10 ฀kg฀, (4)฀ 2฀×฀105฀kg, 77. A฀ certain฀ grade฀ coal฀ contains฀ 1.6฀ per฀ cent฀ sulphur.฀, Assuming฀that฀on฀burning฀the฀coal,฀S฀in฀it฀is฀oxidised฀, to฀SO2,฀how฀many฀moles฀of฀SO2฀would฀be฀formed฀on฀, burning฀1฀metric฀ton฀(1000฀kg)฀of฀coal?, (1)฀ 16฀, , ฀, , (2)฀ 16000 ×, , (3)฀ 16000 ×, , 2, ฀, 32, , (4)฀, , 2, 64, , 16000, 64, , 78. The฀ amount฀ of฀ a฀ given฀ product฀ calculated฀ to฀ be฀ ob­, tained฀in฀a฀chemical฀reaction฀that฀goes฀to฀completion฀is฀, (1)฀ The฀per฀cent฀efficiency฀of฀the฀reaction฀, (2)฀ The฀yield฀of฀the฀reaction฀, (3)฀ The฀theoretical฀yield฀of฀the฀reaction, (4)฀ None฀of฀the฀above, 79. 5.6฀g฀of฀carbon฀monoxide฀is฀heated฀with฀excess฀of฀O2฀, to฀form฀carbon฀dioxide.฀What฀is฀the฀theoretical฀yield฀in฀, grams฀of฀carbon฀dioxide฀(2CO฀+฀O2฀ , → ฀2CO2)?, (1)฀ 44฀g฀ ฀ ฀(2)฀ 88฀g฀ ฀ (3)฀ 4.4฀g฀ ฀ (4)฀ 8.8฀g

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1.12 Objective Chemistry - Vol. I, , 80. Lactose฀ commonly฀ used฀ as฀ a฀ binder฀ in฀ tablets฀ has฀ a฀, molecular฀weight฀342.฀What฀weight฀of฀CO2฀would฀be฀, formed฀ when฀ 1/12฀ mole฀ of฀ this฀ compound฀ is฀ burnt฀, completely?, → ฀12CO2฀+฀11H2O), (C12H22O11฀+฀12O2฀ , (1)฀12฀g฀, ฀, (2)฀ 44฀g฀, (3)฀ 4.4฀g฀, ฀, (4)฀ 440฀g, , 88. A฀ mixture฀ of฀ 20฀ ml฀ of฀ methane฀ and฀ 20฀ ml฀ of฀ O2฀ is฀, ฀exploded฀ and฀ cooled฀ to฀ room฀ temperature.฀ If฀ the฀, ฀reaction฀between฀the฀two฀substances฀is฀written฀as฀, CH4฀+฀2O2฀ , → ฀CO2฀+฀2H2O, then฀the฀final฀volume฀of฀the฀gaseous฀mixture฀is, (1)฀ 10฀ml฀ ฀, (2)฀ 20฀ml, (3)฀ 30฀ml฀ ฀, (4)฀ 60฀ml, , 81. What฀mole฀ratio฀of฀molecular฀chlorine฀(Cl2)฀to฀molec­, ular฀oxygen฀(O2)฀would฀result฀from฀the฀breakup฀of฀the฀, compound฀Cl2O7?, (1)฀ 1:1฀ ฀ (2)฀ 7:2฀ ฀ (3)฀ 1:3.5฀ ฀ (4)฀ 2:4, , 89. Find฀the฀number฀of฀moles฀of฀KClO3฀required฀to฀com­, plete฀the฀reaction, KClO3฀+฀C12H22O11฀ , → ฀KCl฀+฀CO2฀+฀H2O, , 82. When฀100฀g฀of฀ethylene฀polymerises฀to฀polyethylene฀, according฀ to฀ the฀ equation฀ nCH2฀ =฀ CH2฀ , → ........฀, (.....฀CH2–CH2฀...)n฀.....฀the฀weight฀of฀polyethylene฀pro­, duced฀will฀be, n, (1)฀ gm ฀฀ ฀, (2)฀ 100฀g, 2, 100, (3)฀, g฀ ฀, (4)฀ 100฀ng, n, 83. How฀many฀moles฀of฀Fe2+฀ions฀are฀formed฀when฀excess฀, of฀iron฀is฀treated฀with฀50฀ml฀of฀4.0฀M฀HCl฀under฀inert฀, atmosphere?฀Assume฀no฀change฀in฀volume., (1)฀ 0.4฀ ฀ (2)฀ 0.1฀ ฀ (3)฀ 0.2฀ ฀ (4)฀ 0.8, → ฀ 2CO฀ is฀ carried฀ out฀ by฀, 84. The฀ reaction฀ 2C฀ +฀ O2฀ , taking฀24฀g฀of฀carbon฀and฀96฀g฀of฀O2.฀Which฀one฀is฀the฀, limiting฀reagent?, (1)฀ C฀ ฀ (2)฀ O2฀ ฀ (3)฀ CO2฀ ฀ (4)฀ None, → ฀C,฀5฀moles฀of฀A฀and฀8฀, 85. For฀the฀reaction฀A฀+฀2B฀ , moles฀of฀B฀will฀produce, (1)฀ 5฀moles฀of฀C฀, (2)฀ 4฀moles฀of฀C, (3)฀ 8฀moles฀of฀C฀, (4)฀ 13฀moles฀of฀C, 3, 86. The฀equation฀2Al(s)฀+฀ ฀O2(g)฀→฀Al2O3(s)฀shows฀that, 2, (1)฀ ฀2฀moles฀of฀Al฀react฀with฀3/2฀mole฀of฀O2฀to฀produce฀, 7/2฀mole฀of฀Al2O3, (2)฀ ฀2฀ g฀ of฀Al฀ react฀ with฀ 3/2฀ mole฀ of฀ O2฀ to฀ produce฀, 1฀mole฀of฀Al2O3, (3)฀ ฀2฀g฀mole฀of฀Al฀react฀with฀3/2฀litre฀of฀O2฀to฀produce฀, 1฀mole฀of฀Al2O3, (4)฀ ฀2฀moles฀of฀Al฀react฀with฀3/2฀mole฀of฀O2฀to฀produce฀, 1฀mole฀of฀Al2O3, 87. Element฀ A฀ (atomic฀ weight฀ 12.01)฀ and฀ element฀ B฀, (atomic฀weight฀16)฀combine฀to฀form฀a฀new฀substance฀, X.฀ If฀ two฀ moles฀ of฀ B฀ combines฀ with฀ one฀ mole฀ of฀A,฀, then฀the฀weight฀of฀one฀mole฀of฀X฀is, (1)฀ 28.01฀g฀ ฀, (2)฀ 44.01฀g, (3)฀ 40.02฀g฀ ฀, (4)฀ 56.02฀g, , (1)฀ 8฀ ฀ (2)฀ 7฀ ฀ (3)฀ 4฀ ฀ (4)฀ 2, 90. The฀ weight฀ of฀ magnesium฀ that฀ will฀ be฀ required฀ to฀, produce฀ just฀ sufficient฀ hydrogen,฀ from฀ an฀ acid฀ to฀, combine฀with฀all฀the฀oxygen฀that฀can฀be฀obtained฀by฀, the฀ complete฀ decomposition฀ of฀ 24.5฀ g฀ of฀ potassium฀, chlorate฀is, (1)฀10.4฀g฀ ฀, (2)฀ 14.4฀g฀, (3)฀ 9.32฀g฀ ฀, (4)฀ 12.4฀g, 91. 10฀g฀of฀carbon฀burns฀giving฀11.2฀litres฀of฀CO2฀at฀NTP.฀, After฀combustion,฀the฀amount฀of฀unburnt฀carbon฀is฀, (1)฀ 2.5฀g฀ ฀ (2)฀ 4฀g฀ ฀ (3)฀ 3฀g฀ ฀ (4)฀ 1฀g, 92. The฀weight฀of฀MnO2฀required฀to฀produce฀1.78฀litres฀of฀, chlorine฀gas฀at฀STP฀according฀to฀the฀reaction, MnO2฀+฀4HCl฀ , → ฀MnCl2฀+฀2H2O฀+฀Cl2฀is, (1)฀ 6.905฀g฀ ฀, (2)฀ 5.905฀g, (3)฀ 6.509฀g฀ ฀, (4)฀ 6.059฀g, 93. 100฀ g฀ potassium฀ hydrogen฀ carbonate฀ on฀ strong฀ heat­, ing฀gives฀69฀g฀of฀a฀solid฀residue.฀The฀equation฀which฀, represents฀the฀reaction฀is฀, (1)฀ KHCO3฀ , → ฀K2CO3฀+฀H2O฀+฀CO2, → ฀K2CO3฀+฀H2, (2)฀ 2KHCO3฀ , 1, 1, 1, → ฀ ฀K2CO3฀+฀ ฀H2O฀+฀ ฀CO2, (3)฀ KHCO3฀ , 2, 2, 2, → ฀2KOH฀+฀2CO2, (4)฀ 2KHCO3฀ , 94. Chlorophyll฀contains฀2.68%฀of฀magnesium.฀The฀num­, ber฀of฀magnesium฀atoms฀present฀in฀2฀g฀of฀chlorophyll฀is฀, (1)฀ 1.34฀×฀1021฀, (2)฀ 6฀×฀1020, 22, (3)฀ 5.34฀×฀10 ฀, (4)฀ 5.34฀×฀1023, 95. 100฀ml฀of฀0.2M฀K2SO4฀is฀diluted฀with฀100฀ml฀of฀water.฀, The฀K+฀ion฀in฀the฀solution, (1)฀ 0.4M฀ (2)฀ 0.1M฀ (3)฀ 0.2M฀ (4)฀ 0.8M, , answers, (66)฀ 1฀, (71)฀ 3฀, , (67)฀ 2฀, (72)฀ 2฀, , (68)฀ 1฀, (73)฀ 2฀, , (69)฀ 3฀, (74)฀ 2฀, , (70)฀ 2, (75)฀ 1

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Basic Concepts of Chemistry 1.13, , (76)฀ 2฀, (81)฀ 3฀, (86)฀ 4฀, (91)฀ 2฀, , (77)฀ 2฀, (82)฀ 2฀, (87)฀ 2฀, (92)฀ 1฀, , (78)฀ 3฀, (83)฀ 2฀, (88)฀ 2฀, (93)฀ 3฀, , (79)฀ 4฀, (84)฀ 1฀, (89)฀ 1฀, (94)฀ 1฀, , (80)฀ 2, (85)฀ 2, (90)฀ 2, (95)฀ 3, , Practice exercise Level-1, 1. In฀ a฀ sample฀ of฀ pure฀ compound,฀ Na฀ =฀ 0.0887฀ mole,฀, O฀=฀0.132฀mole฀and฀C฀=฀2.65฀1022฀atoms.฀The฀empiri­, cal฀formula฀of฀the฀compound฀is, (1)฀ Na2CO3, (2)฀ Na3O2C5, (3)฀ Na0.0887฀O0.132฀C2.65฀×1022, (4)฀ NaCO, 2. The฀numbers฀of฀atoms฀of฀Cr฀and฀O฀are฀4.8฀×฀1010฀and฀, 9.6฀×฀1010,฀respectively.฀The฀empirical฀formula฀is, (1)฀ Cr2O3฀ ฀, (2)฀ CrO2฀, (3)฀ Cr2O4฀ ฀, (4)฀ None฀of฀these, 3. One฀atom฀of฀an฀element฀A฀weighs฀6.644฀×฀10–23฀g.฀The฀, gram฀atoms฀of฀the฀same฀element฀in฀40฀kg฀will฀be, (1)฀ 40฀, ฀, (2)฀ 400฀, (3)฀ 4000฀ ฀, (4)฀ 1000, 4. Atomicity฀of฀oleum฀is, (1)฀ 11฀ ฀ (2)฀ 8฀ ฀ (3)฀ 7฀ ฀ (4)฀ 18, 5. When฀water฀is฀electrolysed,฀hydrogen฀and฀oxygen฀were฀, obtained฀ which฀ were฀ collected฀ and฀ found฀ to฀ be฀ 16.8฀, litres฀at฀STP.฀Then,฀the฀weight฀of฀water฀electrolysed฀is, (1)฀ 18฀g฀ ฀ (2)฀ 36฀g฀ ฀ (3)฀ 9฀g฀ ฀ (4)฀ 45฀g, 6. 3.2฀g฀of฀a฀hydrated฀salt฀lost฀1.8฀g฀of฀H2O฀on฀heating.฀, Molecular฀ weight฀ of฀ the฀ anhydrous฀ salt฀ is฀ 160.฀ The฀, number฀of฀moles฀of฀water฀of฀crystallisation฀is, (1)฀ 2฀ ฀ (2)฀ 3฀ ฀ (3)฀ 5฀ ฀ (4)฀ 10, 7. 0.3฀mole฀of฀hydrocarbon฀on฀combustion฀gave฀26.4฀g฀, of฀CO2.฀If฀that฀hydrocarbon฀decolourises฀Bayer’s฀rea­, gent฀and฀gave฀a฀precipitate฀with฀Tollen’s฀reagent,฀the฀฀, molecular฀weight฀of฀hydrocarbon฀is, (1)฀ 28฀ ฀ (2)฀ 26฀ ฀ (3)฀ 30฀ ฀ (4)฀ 14, 8. A฀ compound฀ has฀ 50%฀ of฀A฀ (at.฀ wt.฀ 20)฀ and฀ 50%฀ B฀฀, (at.฀wt.฀30).฀If฀the฀molecule฀of฀the฀compound฀contains฀, 6฀atoms฀of฀A,฀then฀the฀molecular฀formula฀is, (1)฀ A4B6฀ ฀ (2)฀ A6B4฀ ฀ (3)฀ A3B8฀ ฀ (4)฀ A6B2, 9. A฀vessel฀contains฀0.32฀g฀of฀O2฀and฀under฀similar฀con­, ditions฀ another฀ vessel฀ contains฀ 0.26฀ g฀ of฀ compound฀, X.฀ If฀ X฀ contains฀ C฀ and฀ H฀ in฀ 1:1,฀ then฀ the฀ molecular฀, ฀formula฀of฀X฀is, , (1)฀ C6H6฀, (3)฀ C2H2฀, , ฀, ฀, , (2)฀ C8H8฀, (4)฀ Any฀one฀of฀these, , 10. If฀an฀iodised฀salt฀contains฀1%฀of฀KI฀and฀a฀person฀takes฀, 2.5฀g฀of฀the฀salt฀every฀day,฀the฀iodide฀ions฀going฀into฀, his฀or฀her฀body฀every฀day฀would฀be฀approximately, (1)฀ 7.2฀×฀1021฀, (2)฀ 7.2฀×฀1019, 21, (3)฀ 3.6฀×฀10 ฀, (4)฀ 9.03฀×฀1019, 11. A฀mixture฀of฀magnesium฀chloride฀and฀magnesium฀sul­, phate฀is฀known฀to฀contain฀0.6฀moles฀of฀chlorides฀ions฀, and฀0.2฀moles฀of฀sulphate฀ions.฀The฀number฀of฀moles฀, of฀magnesium฀ions฀present฀is, (1)฀ 0.4฀฀ ฀ (2)฀ 0.5฀฀ ฀ (3)฀ 0.8฀ ฀ (4)฀ 1.0, 12. A฀ sample฀ of฀ ammonium฀ phosphate฀ contains฀ 3.18฀, moles฀ of฀ hydrogen฀ atoms.฀ The฀ number฀ of฀ moles฀ of฀, oxygen฀atoms฀in฀the฀sample฀is, (1)฀ 0.265฀฀ ฀ (2)฀ 0.795฀ ฀ (3)฀ 1.06฀ ฀ ฀(4)฀ 3.18, 13. Which฀ of฀ the฀ following฀ statements฀ about฀Avagodro’s฀, constant฀is฀true?, (1)฀ ฀It฀ is฀the฀number฀ of฀electrons฀ required฀ to฀deposit฀, one฀mole฀of฀atoms฀of฀any฀metallic฀element฀from฀a฀, solution฀of฀one฀of฀its฀salts., (2)฀ ฀It฀is฀the฀number฀of฀atoms฀contained฀in฀one฀mole฀of฀, atoms฀of฀any฀monoatomic฀element., (3)฀ ฀It฀is฀the฀number฀of฀grams฀of฀any฀element฀which฀, contains฀6.02฀×฀1023฀atoms฀of฀the฀element., (4)฀ ฀It฀ is฀ the฀ number฀ of฀ particles฀ (ions,฀ atoms฀ and฀, molecules)฀required฀to฀make฀one฀gram฀of฀the฀sub­, stance฀under฀consideration., 14. The฀number฀of฀moles฀of฀oxygen฀in฀1฀litre฀of฀air฀contain­, ing฀21%฀oxygen฀by฀volume฀in฀standard฀conditions฀is, (1)฀ 0.186฀mol฀, ฀, (2)฀ 0.21฀mol, (3)฀ 2.1฀moles฀, ฀, (4)฀ 0.0093฀mol, 15. On฀ mixing฀ equal฀ volumes฀ of฀ 0.08฀ M฀ Pb(NO3)2฀ and฀฀, 0.1฀ M฀ KIO3,฀ a฀ white฀ Pb(IO3)2฀ precipitates.฀ Assum­, ing฀ the฀ reaction฀ goes฀ to฀ completion,฀ the฀ ratio฀ of฀ the฀, ฀, number฀of฀moles฀of฀Pb(IO3)2฀to฀the฀number฀of฀moles฀, of฀the฀reactant฀left฀unreacted฀is, (1)฀ 10/3฀ ฀ (2)฀ 5/3฀ ฀ (3)฀ 2/3฀ ฀ (4)฀ 3/10, 16. The฀number฀of฀moles฀of฀H2O฀formed฀when฀0.1฀mole฀of฀, Ba(OH)2฀is฀treated฀with฀0.25฀mole฀of฀HClO3฀according฀, to฀the฀equation, → ฀Ba(ClO3)2฀+฀2H2O฀is, Ba(OH)2฀+฀2HClO3฀ , (1)฀ 0.05฀ ฀ (2)฀ 0.2฀ ฀ (3)฀ 0.15฀ ฀ (4)฀ 0.3, 17. The฀ reaction฀ between฀ aluminium฀ metal฀ and฀ dilute฀, ฀hydrochloric฀ acid฀ produced฀ H2฀ and฀ Al3+฀ ions.฀ The฀, ฀molar฀ratio฀of฀aluminium฀used฀to฀produce฀hydrogen฀is, (1)฀ 1:2฀ ฀ (2)฀ 2:1฀ ฀ (3)฀ 3:2฀ ฀ (4)฀ 2:3

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1.14 Objective Chemistry - Vol. I, , 18. Equal฀ volumes฀ of฀ 0.2M฀ HCl฀ and฀ 0.4M฀ KOH฀ are฀, mixed.฀The฀concentrations฀of฀the฀principal฀ions฀in฀the฀, resulting฀solutions฀are, (1)฀ [K+]฀=฀0.4M;฀[Cl–]฀=฀0.2M;฀[H+]฀=฀0.2M, (2)฀ [K+]฀=฀0.2M;฀[Cl–]฀=฀0.1M;฀[OH–]฀=฀0.1M, (3)฀ [H+]฀=฀0.1M;฀[Cl–]฀=฀0.1M;฀[OH–]฀=฀0.1M, (4)฀ [H+]฀=฀0.2M;฀[Cl–]฀=฀0.1M;฀[H+]฀=฀0.1M, 19. Zinc฀reacts฀with฀CuSO4฀according฀to฀the฀equation฀Zn฀+฀, CuSO4฀ , → ฀ ZnSO4฀ +฀ Cu.฀ If฀ excess฀ zinc฀ is฀ added฀, to฀ 100฀ ml฀ of฀ 0.05฀ M฀ CuSO4฀ solution,฀ the฀ amount฀ of฀, copper฀formed฀is฀, 1, 1, (1)฀, moles ฀, moles, ฀, (2)฀, 200, 250, 200, 7, (3)฀, moles ฀, moles, ฀, (4)฀, 7, 200, 20. 2.79฀g฀of฀iron฀is฀completely฀converted฀into฀rust฀(Fe2O3).฀, The฀weight฀of฀oxygen฀in฀the฀rust฀(At.฀Wt.฀of฀Fe฀=฀55.8)฀is, (1)฀ 2฀g฀ ฀ (2)฀ 1.2฀g฀ ฀ (3)฀ 3฀g฀ ฀ (4)฀ 1.8฀g, 21. A฀compound฀contains฀69.5%฀oxygen฀and฀30.5%฀nitro­, gen฀and฀its฀molecular฀weight฀is฀92.฀The฀formula฀of฀the฀, compound฀is฀, (1)฀ N2O฀, ฀, (2)฀ N2O3฀, (3)฀ N2O4฀, ฀, (4)฀ N2O5, 22. One฀ mole฀ mixture฀ of฀ CO฀ and฀ CO2฀ requires฀ exactly฀, 20฀ g฀ of฀ NaOH฀ to฀ convert฀ all฀ the฀ CO2฀ into฀ Na2CO3.฀, How฀many฀more฀grams฀of฀NaOH฀would฀it฀require฀for฀, conversion฀into฀Na2CO3,฀if฀the฀mixture฀is฀completely฀, ฀oxidised฀to฀CO2?, (1)฀ 80฀g฀ ฀ (2)฀ 60฀g฀ ฀ (3)฀ 40฀g฀ ฀ (4)฀ 20฀g, 23. The฀correct฀arrangement฀of฀the฀following฀in฀order฀of฀, increasing฀mass฀is, ฀฀฀I.฀฀Nitrogen฀molecule, ฀฀II.฀฀Oxygen฀atom, III.฀ 1฀Avogram, IV.฀ 1฀×฀10–10฀g฀atoms฀of฀copper, (1)฀ I฀>฀II฀>฀III฀>฀IV฀ ฀, (2)฀ I฀<฀II฀<฀III฀<฀IV, (3)฀ III฀<฀II฀<฀I฀<฀IV฀ ฀, (4)฀ II฀<฀III฀<฀I฀<฀IV, , 26. 10฀ grams฀ of฀ CaCO3฀ is฀ completely฀ decomposed฀ to฀ X฀, and฀CaO.฀X฀is฀passed฀into฀an฀aqueous฀solution฀contain­, ing฀one฀mole฀of฀sodium฀carbonate.฀What฀is฀the฀number฀, of฀ moles฀ of฀ sodium฀ bicarbonate฀ formed฀ (Mol.฀ Wts.:฀, CaCO3฀=฀100;฀Na2CO3฀=฀106฀and฀NaHCO3฀=฀84)?฀, (1)฀0.2฀ ฀ (2)฀ 0.1฀ ฀ (3)฀ 0.01฀ ฀ (4)฀ 10, 27. Study฀the฀following฀table, Compound, Mol. Wt., , Weight of compound, Taken (in g), , I, , CO2฀(44), , 4.4, , II, , NO2฀(46), , 2.3, , III, , H2O2฀(34), , 6.8, , IV, , SO2฀(64), , 1.6, , Which฀two฀compounds฀have฀the฀least฀weight฀of฀oxy­, gen?฀ (Molecular฀ weights฀ of฀ compounds฀ are฀ given฀ in฀, brackets.), (1)฀ II฀and฀IV฀, ฀, (2)฀ I฀and฀III, (3)฀ I฀and฀II฀ ฀, ฀, (4)฀ III฀and฀IV, 28. In฀ the฀ decomposition฀ of฀ 10฀ g฀ of฀ MgCO3,฀ 0.1฀ mol฀ of฀, CO2฀and฀4.0฀g฀of฀MgO฀are฀obtained.฀Hence,฀the฀per­, centage฀purity฀of฀MgCO3฀is, (1)฀ 50%฀ ฀ (2)฀ 60%฀ ฀ (3)฀ 40%฀ ฀ (4)฀ 84%, 29. In฀which฀case฀the฀purity฀of฀a฀substance฀is฀100%?, (1)฀ 1฀mole฀of฀CaCO3฀gave฀11.2฀L฀of฀CO2฀(at฀STP), (2)฀ 1฀mole฀of฀MgCO3฀gave฀40.0฀g฀of฀MgO, (3)฀ 1฀mole฀of฀NaHCO3฀gave฀4฀g฀of฀H2O, (4)฀ 1฀mole฀of฀Ca(HCO3)2฀gave฀1฀mole฀of฀CO2, 30. X+,฀Y2+฀ and฀ Z–฀ are฀ isoelectronic฀ of฀ CO2.฀ Increasing฀฀, order฀of฀protons฀in฀X+,฀Y2+฀and฀Z–฀is฀, ฀, (1)฀ X+฀=฀Y2+฀=฀Z–฀, (2)฀ X–฀<฀Y2+฀<฀Z–, –, +, 2+, (3)฀ Z ฀<฀X ฀<฀Y ฀, ฀, (4)฀ Y2+฀<฀X+฀<฀Z–, 31. Per฀cent฀yield฀of฀NH3฀in฀the฀following฀reaction฀is฀80%:฀, → ฀ Na2CO3฀ +฀ 2NH3.฀ If฀, NH2CONH2฀ +฀ 2NaOH฀ ∆, 6฀g฀of฀NH2CONH2฀react฀with฀8฀g฀of฀NaOH฀the฀NH3฀฀, formed฀is, (1)฀ 3.4฀g฀, (2)฀ 2.72฀g฀ (3)฀ 4.25฀g฀ (4)฀ 11.2฀g, , 24. C­12฀ and฀ C­14฀ isotopes฀ are฀ found฀ as฀ 98%฀ and฀ 2%,฀, respectively฀in฀any฀sample.฀Then฀the฀number฀of฀C­14฀, atoms฀in฀12฀g฀of฀the฀sample฀will฀be, (1)฀ 1.5฀mole฀atoms฀ ฀, (2)฀ 1.032฀×฀1022฀atoms, 21, (3)฀ 2.06฀of฀×฀10 ฀atoms฀, (4)฀ 2฀g฀atom, , 32. Cortisone฀ is฀ a฀ molecular฀ substance฀ containing฀ 21฀, ฀atoms฀of฀carbon฀per฀molecule.฀The฀mass฀percentage฀of฀, carbon฀in฀cortisone฀is฀69.98%.฀Its฀molar฀mass฀is, (1)฀ 176.5฀ (2)฀ 252.2฀ (3)฀ 287.6฀, (4)฀ 360.1, , 25. A฀ sample฀ of฀ copper฀ sulphate฀ pentahydrate฀, (CuSO4฀.฀5H2O)฀contains฀3.2฀g฀of฀Cu฀(Atomic฀weight฀, =฀64).฀How฀many฀grams฀of฀O2฀are฀in฀this฀sample?, (1)฀7.2฀g฀ ฀ (2)฀ 3.2฀g฀ ฀ (3)฀ 14.4฀g฀ ฀ (4)฀ 0.8฀g, , 33. One฀mole฀of฀BaF2฀is฀treated฀with฀2฀moles฀of฀H2SO4.฀To฀, make฀the฀resulting฀mixture฀neutral,฀NaOH฀is฀added.฀The฀, number฀of฀moles฀of฀NaOH฀required฀in฀this฀process฀is, (1)฀ 4฀ ฀ (2)฀ 2฀ ฀ (3)฀ 3฀ ฀ (4)฀ 1

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Basic Concepts of Chemistry 1.15, , 34. If฀m฀gram฀of฀a฀metal฀A฀displaces฀m2฀gram฀of฀another฀, metal฀ B฀ from฀ its฀ salt฀ solution฀ and฀ if฀ the฀ equivalent฀, weights฀are฀E1฀and฀E2,฀respectively฀then฀the฀equivalent฀, weight฀of฀A฀can฀be฀expressed฀by฀, m, m × E2, (1)฀ E1 = 1 × E2 ฀, ฀, (2)฀ E1 = 2, m2, m1, (3)฀ E1 =, , m1 × m2, ฀, E2, , ฀, , (4)฀ E1 =, , m1, × E2, m2, , 35. If฀Al,฀Zn฀and฀Fe฀scraps฀has฀the฀same฀rate฀per฀Kg฀then฀, for฀the฀production฀of฀H2฀by฀the฀action฀of฀dilute฀H2SO4, (1)฀ Fe฀will฀be฀cheapest฀and฀Al฀will฀be฀costliest, (2)฀ Al฀will฀be฀cheapest฀and฀zinc฀will฀be฀costliest, (3)฀ Fe฀will฀be฀cheapest฀and฀zinc฀will฀be฀costliest, (4)฀ Zn฀will฀be฀cheapest฀and฀Al฀will฀be฀costliest, 36. Choose฀the฀correct฀statement:, ฀ ฀ The฀ use฀ of฀ 12C฀ scale฀ has฀ superseded฀ the฀ older฀ scale฀, of฀ atomic฀ mass฀ based฀ on฀ 16O฀ isotope,฀ one฀ important฀, advantage฀of฀the฀former฀being, (1)฀ T, ฀ he฀ atomic฀ masses฀ on฀ 12C฀ scale฀ became฀ whole฀, numbers.฀, (2)฀ 12C฀is฀more฀abundant฀in฀the฀earth’s฀crust฀than฀16O., (3)฀ ฀The฀ difference฀ between฀ physical฀ and฀ chemical฀, atomic฀masses฀got฀narrowed฀down฀significantly., (4)฀ 12, ฀ C฀is฀situated฀midway฀between฀metals฀and฀non­, metals฀in฀the฀periodic฀table., 37. 2.2฀g฀of฀compounds฀of฀phosphorous฀and฀sulphur฀con­, tain฀1.24฀g฀of฀phosphorous.฀The฀empirical฀formula฀of฀, the฀compound฀is, (1)฀ P4S3฀, (2)฀ P3S4฀, (3)฀ P3S2฀, (4)฀ P2S3, 38. 0.1฀ mole฀ of฀ a฀ compound฀ containing฀ sulphur฀ and฀, chlorine฀ is฀ subjected฀ to฀ a฀ number฀ of฀ chemical฀ reac­, tions฀ which฀ resulted฀ in฀ the฀ precipitation฀ of฀ 0.1฀ mole฀, of฀PbCl2฀and฀0.2฀mole฀of฀BaSO4.฀The฀formula฀of฀the฀, original฀compound฀is, (1)฀ SCl2฀, ฀, (2)฀ S2Cl2฀, (3)฀ SCl4฀, ฀, (4)฀ S2Cl, 39. Under฀ the฀ same฀ conditions฀ of฀ temperature฀ and฀ pres­, sure,฀ equal฀ volumes฀ of฀ oxygen฀ and฀ hydrocarbon฀, weights฀ are฀ 0.32฀ g฀ and฀ 0.26฀ g,฀ respectively.฀The฀ for­, mula฀of฀hydrocarbon฀is, (1)฀ C2H4฀ ฀ (2)฀ C2H6฀ ฀ (3)฀ C2H2฀ ฀ (4)฀ CH4, 40. Comparing฀ CO,฀ CO2,฀ HCHO฀ and฀ CH4฀ the฀ per฀ cent฀, composition฀of฀carbon฀is฀maximum฀in, (1)฀ CO฀ ฀ (2)฀ CO2฀ ฀ (3)฀ HCHO฀ ฀ (4)฀ CH4, 41. 0.01฀mole฀of฀iodoform฀(CHI3)฀reacts฀with฀Ag฀powder฀, to฀produce฀a฀gas฀whose฀volume฀at฀STP฀is, , (1)฀ 224฀mL฀ ฀, (3)฀ 336฀mL฀ ฀, , (2)฀ 112฀mL฀, (4)฀ none฀of฀these, , 42. Which฀among฀MnO2,฀Mn2O3,฀MnO3฀and฀Mn2O7฀con­, tains฀the฀maximum฀percentage฀by฀weight฀of฀combined฀, oxygen?, (1)฀ MnO2฀ ฀, (2)฀ Mn2O3, (3)฀ MnO3฀ ฀, (4)฀ Mn2O7, 43. Three฀ samples฀ of฀ iron฀ of฀ equal฀ weights฀ are฀ used฀ to฀, form฀FeO,฀Fe2O3฀and฀Fe3O4฀independently.฀Then,฀the฀, amount฀(in฀grams)฀of฀O2฀required฀is, (1)฀ maximum฀for฀the฀formation฀of฀Fe3O4, (2)฀ maximum฀for฀the฀formation฀of฀Fe2O3, (3)฀ minimum฀for฀the฀formation฀of฀Fe2O3, (4)฀ the฀same฀for฀the฀formation฀of฀all฀the฀three, 44. On฀ analysis,฀ a฀ certain฀ compound฀ was฀ found฀ to฀ con­, tain฀iodine฀and฀oxygen฀in฀the฀ratio฀254฀g฀of฀iodine฀and฀, 80฀g฀of฀oxygen.฀The฀atomic฀mass฀of฀iodine฀is฀127฀and฀, that฀of฀oxygen฀is฀16.฀Which฀is฀the฀formula฀of฀the฀com­, pound?, (1)฀ IO฀ ฀ (2)฀ I2O฀ ฀ (3)฀ I5O2฀ ฀ (4)฀ I2O5, 45. A฀ metal฀ M฀ forms฀ a฀ chloride฀ MCl2,฀ the฀ formula฀ of฀, phosphoric฀acid฀is฀H3PO4.฀The฀formula฀of฀phosphate฀, of฀the฀metal฀is, (1)฀ MPO4฀ ฀, (2)฀ M2PO4, (3)฀ M3(PO4)2฀, (4)฀ M(PO4)2, 46. A฀ compound฀ of฀ carbon,฀ hydrogen฀ and฀ nitrogen฀ con­, tains฀three฀elements฀in฀the฀respective฀ratio฀of฀9:1:3.5.฀, Its฀empirical฀formula฀is, (1)฀ C3H4N฀ ฀, (2)฀ C2H4N, (3)฀ CH2N฀ ฀, (4)฀ C3H6N, 47. In฀a฀gaseous฀reaction฀of฀the฀type, → ฀cC฀+฀dD, aA฀+฀bB฀ , which฀is฀wrong?, (1)฀ ฀a฀ litre฀ of฀ A฀ combines฀ with฀ b฀ litre฀ of฀ B฀ to฀ give฀, C฀and฀D, (2)฀ ฀a฀mole฀of฀A฀combines฀with฀b฀mole฀of฀B฀to฀give฀, C฀and฀D, (3)฀ ฀a฀gram฀of฀A฀combines฀with฀b฀gram฀of฀B฀to฀give฀, C฀and฀D, (4)฀ ฀a฀ molecules฀ of฀A฀ combine฀ with฀ b฀ molecules฀ of฀, B฀to฀give฀C฀and฀D, 48. Which฀of฀the฀following฀about฀chemical฀equation฀is฀false?, (1)฀ ฀It฀generally฀describes฀only฀the฀overall฀change,฀that฀, is฀the฀number฀of฀atoms,฀molecules฀or฀ions฀before฀, and฀after฀a฀reaction., (2)฀ ฀It฀ indicates฀ nothing฀ about฀ how฀ products฀ are฀, formed฀from฀reactants.

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1.16 Objective Chemistry - Vol. I, , (3)฀ I฀ t฀does฀not฀show฀how฀long฀it฀will฀take฀for฀the฀reac­, tion฀to฀occur., (4)฀ ฀It฀cannot฀indicate฀the฀actual฀mole฀ratio฀in฀which฀, reactants฀react., 49. Sodium฀combines฀with฀35Cl฀and฀37Cl฀to฀give฀two฀sam­, ples฀of฀NaCl.฀Their฀formation฀follows฀the฀law฀of, (1)฀ Definite฀proportions, (2)฀ Multiple฀proportions, (3)฀ Reciprocal฀proportions, (4)฀ None฀of฀these, 50. Gay฀ Lussac’s฀ law฀ is฀ not฀ applicable฀ for฀ those฀ gases฀, which฀on฀mixing, (1)฀ do฀not฀react, (2)฀ diffuse, (3)฀ react฀with฀each฀other, (4)฀ all฀are฀wrong, , answers, ฀ (1)฀ 1฀, ฀ (6)฀ 3฀, (11)฀ 2฀, (16)฀ 2฀, (21)฀ 3฀, (26)฀ 1฀, (31)฀ 2฀, (36)฀ 3฀, (41)฀ 2฀, (46)฀ 1฀, , ฀ (2)฀ 2฀, ฀ (7)฀ 2฀, (12)฀ 3฀, (17)฀ 4฀, (22)฀ 2฀, (27)฀ 1฀, (32)฀ 4฀, (37)฀ 1฀, (42)฀ 4฀, (47)฀ 3฀, , ฀ (3)฀ 5฀, ฀ (8)฀ 2฀, (13)฀ 2฀, (18)฀ 2฀, (23)฀ 3฀, (28)฀ 4฀, (33)฀ 1฀, (38)฀ 2฀, (43)฀ 2฀, (48)฀ 4฀, , ฀ (4)฀ 1฀, ฀ (9)฀ 3฀, (14)฀ 4฀, (19)฀ 1฀, (24)฀ 2฀, (29)฀ 2฀, (34)฀ 1฀, (39)฀ 3฀, (44)฀ 4฀, (49)฀ 1฀, , ฀ (5)฀ 3, (10)฀ 4, (15)฀ 2, (20)฀ 2, (25)฀ 1, (30)฀ 3, (35)฀ 2, (40)฀ 4, (45)฀ 3, (50)฀ 3, , Practice exercise Level-II, 1. The฀vapour฀density฀of฀completely฀dissociated฀NH4Cl฀, would฀be฀, (1)฀ Half฀that฀of฀NH4Cl, (2)฀ less฀than฀half฀that฀of฀NH4Cl, (3)฀ more฀than฀half฀that฀of฀NH4Cl, (4)฀ depends฀on฀the฀amount฀of฀NH4Cl฀taken฀at฀start, 2. A฀sample฀of฀clay฀was฀partially฀dried.฀It฀contains฀50%฀, silica฀and฀10%฀water.฀The฀original฀clay฀contained฀19%฀, water.฀The฀percentage฀of฀silica฀present฀in฀the฀sample฀is, (1)฀ 45%฀ ฀ (2)฀ 47.3%฀ ฀ (3)฀ 52%฀ ฀ (4)฀ 59.1%, 3. The฀number฀of฀C2O42–฀ions฀in฀100฀ml฀of฀0.2M฀aqeous฀, Na2C2O4฀is฀(assume฀complete฀ionisation), (1)฀ 0.62฀×฀1022฀, ฀, (2)฀ 1.204฀×฀1022, 22, (3)฀ 1.86฀×฀10 ฀, ฀, (4)฀ 18.6฀×฀1022, , 4. A฀1.04฀g฀sample฀of฀a฀metal฀carbonates฀of฀A฀and฀B฀on฀, heating฀gave฀0.6฀g฀of฀mixture฀of฀oxides฀A฀and฀B.฀Given฀, that฀A฀is฀80%฀by฀weight฀and฀B฀is฀60%฀weight฀in฀their฀, oxides,฀then฀the฀composition฀obtained฀and฀final฀mix­, tures฀of฀compounds฀of฀A฀and฀B,฀respectively฀are, (1)฀ 0.62฀g,฀0.42฀g,฀0.4฀g฀and฀0.2฀g, (2)฀ 0.42฀g,฀0.62฀g,฀0.4฀g฀and฀0.2฀g, (3)฀ 0.31฀g,฀0.73฀g,฀0.2฀g฀and฀0.4฀g, (4)฀ None฀of฀these, 5. If฀the฀percentage฀of฀water฀of฀crystallisation฀in฀MgSO4., xH2O฀is฀13%,฀what฀is฀the฀value฀of฀x฀(relative฀atomic฀, masses฀H฀=฀1,฀O฀=฀16,฀Mg฀=฀24฀and฀S฀=฀32)?, (1)฀ 1฀ ฀ (2)฀ 4฀ ฀ (3)฀ 5฀ ฀ (4)฀ 7, 6. Sodium฀ salt฀ of฀ an฀ acid฀ dye฀ contains฀ 7%฀ of฀ sodium.฀, What฀is฀the฀minimum฀molar฀mass฀of฀the฀dye?, (1)฀ 336.5฀ ฀, (2)฀ 286.5, (3)฀ ฀300.6฀ ฀, (4)฀ 306.5, 7. An฀element฀X฀is฀found฀to฀combine฀with฀oxygen฀to฀form฀, X4O6.฀ If฀ 8.4฀ g฀ of฀ this฀ element฀ combine฀ with฀ 6.50฀ g฀ of฀, oxygen,฀then฀the฀atomic฀weight฀of฀the฀element฀in฀grams฀is, (1)฀ 24.0฀ ฀ (2)฀ 31.0฀ ฀ (3)฀ 50.4฀ ฀ (4)฀ 118.7, 8. Using฀scientific฀notation฀1000฀metre฀in฀centimetres฀up฀, to฀two฀significant฀figures฀is฀expressed฀as, (1)฀ 1.0฀×฀104฀, (2)฀ 1฀×฀105, 5, (3)฀ 1.0฀×฀10 ฀, (4)฀ 1.00฀×฀103, 9. Which฀of฀the฀following฀has฀three฀significant฀figures?, (1)฀ 0.52฀, ฀, (2)฀ 543.00, (3)฀ 126฀, ฀, (4)฀ 0.0600, 10. Among฀the฀following฀pairs,฀law฀of฀multiple฀proportion฀, is฀illustrated฀by, (1)฀ H2S฀and฀SO2฀, ฀, (2)฀ BeO฀and฀BeCl2, (3)฀ NH3฀and฀NO2฀ ฀, (4)฀ N2O฀and฀NO, 11. Which฀ of฀ the฀ following฀ statements฀ is฀ true฀ regarding฀, rounding฀off฀the฀digits?, (1)฀ ฀If฀ the฀ digit฀ coming฀ after฀ the฀ desired฀ number฀ of฀, significant฀ figures฀ is฀ more฀ than฀ 5,฀ the฀ preceding฀, digit฀is฀increased฀by฀one., (2)฀ ฀If฀ the฀ digit฀ coming฀ after฀ the฀ desired฀ number฀ of฀, significant฀figure฀is฀less฀than฀5,฀the฀preceding฀digit฀, is฀not฀changed., (3)฀ I฀ f฀the฀digit฀coming฀after฀the฀desired฀number฀of฀sig­, nificant฀figure฀is฀5,฀the฀preceding฀digit฀is฀increased฀, by฀one฀if฀it฀is฀odd฀and฀not฀changed฀if฀it฀is฀even., (4)฀ All฀of฀these., 12. Four฀one­litre฀flasks฀are฀separately฀filled฀with฀the฀gases,฀฀, hydrogen,฀helium,฀oxygen฀and฀ozone฀at฀the฀same฀room฀

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Basic Concepts of Chemistry 1.17, , temperature฀ and฀ pressure.฀ The฀ ratio฀ of฀ total฀ number฀, of฀atoms฀of฀these฀gases฀present฀in฀the฀different฀flasks฀, would฀be, (1)฀ 1:1:฀1:1฀ ฀, (2)฀ 1:2:2:3, (3)฀ 2:1:2:3฀ ฀, (4)฀ 3:2:2:1, 13. If฀ two฀ compounds฀ have฀ the฀ same฀ empirical฀ formula฀, but฀different฀molecular฀formulae,฀they฀must฀have, (1)฀ different฀per฀cent฀compositions, (2)฀ different฀molecular฀weights, (3)฀ same฀viscosity, (4)฀ same฀vapour฀density, 14. If฀1021฀molecules฀are฀removed฀from฀200฀mg฀of฀CO2,฀, then฀the฀number฀of฀moles฀of฀CO2฀left฀is, (1)฀ 2.88฀×฀10–3฀, (2)฀ 4.54฀×฀10–3, –3, (3)฀ 1.66฀×฀10 ฀, (4)฀ 1.66฀×฀10–2, 15. The฀percentage฀composition฀of฀four฀hydrocarbons฀is฀as฀, follows฀, , ฀, , (i), , (ii), , (iii), , (iv), , %฀of฀C, , 75, , 80, , 85.79฀฀฀1.3, , 91.3, , %฀of฀H, , 25, , 20, , 14.3฀฀฀฀฀8.7, , ฀ 8.7, , The฀data฀illustrate฀the฀law฀of฀, (1)฀ constant฀proportions, (2)฀ reciprocal฀proportions, (3)฀ multiple฀proportions, (4)฀ conservation฀of฀energy, , 16. The฀following฀data฀are฀available, (a)฀%฀of฀Mg฀in฀MgO฀and฀in฀MgCl2, (b)฀%฀of฀C฀in฀CO฀and฀CO2, (c)฀%฀of฀K2Cr2O7฀in฀K2CrO4, (d)฀%฀of฀Cu฀isotopes฀in฀copper฀metal, The฀law฀of฀multiple฀proportions฀may฀be฀illustrated฀by฀, the฀data, (1)฀ a฀and฀b฀ ฀, (2)฀ b฀only, (3)฀ a,฀b฀and฀d฀, (4)฀ c฀only, 17. Zinc฀ sulphate฀ contains฀ 22.65%฀ of฀ Zn฀ and฀ 43.9%฀ of฀, H2O.฀ If฀ the฀ law฀ of฀ definite฀ proportions฀ is฀ true,฀ then฀, the฀mass฀of฀zinc฀required฀to฀give฀20฀g฀of฀the฀crystals฀, will฀be, (1)฀ 0.453฀g฀ ฀, (2)฀ 4.53฀g, (3)฀ 45.3฀g฀ ฀, (4)฀ 453฀g, 18. Which฀ of฀ the฀ following฀ is฀ a฀ best฀ example฀ of฀ law฀ of฀, conservation฀of฀mass?, (1)฀ ฀12฀g฀of฀C฀combines฀with฀32฀g฀of฀O2฀to฀form฀44฀g฀, of฀CO2., (2)฀ ฀12฀g฀of฀C฀is฀heated฀in฀vacuum฀there฀is฀no฀change฀, in฀mass., , (3)฀ T, ฀ he฀mass฀of฀a฀piece฀of฀Pt฀is฀the฀same฀before฀and฀, after฀heating., (4)฀ ฀A฀sample฀of฀air฀increases฀in฀volume฀when฀heated฀at฀, constant฀pressure฀but฀the฀mass฀remains฀unchanged., 19. Law฀of฀definite฀proportions฀does฀not฀apply฀to฀nitrogen฀, oxide฀because, (1)฀ Mass฀number฀of฀nitrogen฀is฀not฀constant., (2)฀ Atomic฀weight฀of฀oxygen฀is฀variable., (3)฀ Equivalent฀weight฀of฀nitrogen฀is฀variable., (4)฀ Molecular฀weight฀of฀nitrogen฀is฀not฀fixed., 20. Gay฀Lussac’s฀law฀of฀gaseous฀volume฀is฀derived฀from฀, (1)฀ Law฀of฀definite฀proportions, (2)฀ Law฀of฀multiple฀proportions, (3)฀ Law฀of฀reciprocal฀proportions, (4)฀ Experimental฀observations, 21. The฀composition฀of฀compound฀A฀is฀40%฀x฀and฀60%฀y.฀, The฀composition฀of฀compound฀B฀is฀25%฀x฀and฀75%฀y.฀, According฀to฀the฀law฀of฀multiple฀proportions,฀the฀ratio฀, of฀the฀weight฀of฀element฀y฀in฀compounds฀A฀and฀B฀is฀, (1)฀ 1:2฀ ฀ (2)฀ 2:1฀ ฀ (3)฀ 2:3฀ ฀ (4)฀ 3:4, 22. Equal฀ masses฀ of฀ oxygen,฀ hydrogen฀ and฀ methane฀ are฀, kept฀ under฀ identical฀ conditions.฀The฀ ratio฀ of฀ the฀ vol­, umes฀of฀the฀gases฀will฀be, (1)฀ 2:16:2฀ ฀, (2)฀ 2:16:1, (3)฀ 1:16:2฀ ฀, (4)฀ 1:1:1, 23. H2฀ combines฀ with฀ O2฀ to฀ form฀ H2O฀ in฀ which฀ 16฀ g฀ of฀, oxygen฀combines฀with฀2฀g฀of฀hydrogen.฀H2฀also฀com­, bines฀with฀carbon฀to฀form฀CH4฀in฀which฀2฀g฀of฀hydro­, gen฀combine฀with฀6฀g฀of฀carbon.฀If฀C฀and฀O2฀combine฀, together฀then฀they฀will฀do฀so฀in฀the฀ratio, (1)฀ 6:18฀ ฀ (2)฀ 6:16฀ ฀ (3)฀ 1:2฀ ฀ (4)฀ 12:24, 24. The฀mass฀of฀nitrogen฀per฀gram฀in฀the฀compound฀hydra­, zine฀is฀exactly฀one฀and฀half฀the฀mass฀of฀nitrogen฀in฀the฀, compound฀ammonia.฀The฀fact฀illustrates, (1)฀ Law฀of฀conservation฀of฀mass, (2)฀ Multiple฀valency฀of฀nitrogen, (3)฀ Law฀of฀multiple฀proportions, (4)฀ Law฀of฀definite฀proportions, 25. A฀ sample฀ of฀ AlF3฀ contains฀ 3.0฀ × 1024฀ F−฀ ions.฀ The฀, number฀of฀formula฀units฀in฀this฀sample฀is, (1)฀ 9.0฀×฀1024฀, (2)฀ 3.0฀×฀1024, 24, (3)฀ 0.75฀×฀10 ฀, (4)฀ 1฀×฀1024, 26. 400฀mg฀of฀capsule฀contains฀100฀mg฀of฀ferrous฀fuma­, rate.฀The฀percentage฀of฀iron฀present฀in฀the฀capsule฀is฀, approximately, (1)฀ 8.2%฀ ฀, (2)฀ 25%฀, (3)฀ 16%฀, ฀, (4)฀ unpredictable

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1.18 Objective Chemistry - Vol. I, , 27. Assume฀ that฀ the฀ nucleus฀ of฀ the฀ fluorine฀ atom฀ is฀ a฀, sphere฀of฀radius฀5฀× 10–13฀cm.฀What฀is฀the฀density฀of฀, matter฀in฀the฀nucleus?, (1)฀ 6.02฀×฀1023฀g฀mL–1฀ ฀(2)฀ 6.02฀×฀1013฀g฀mL–1, (3)฀ 12.02฀×฀1023฀g฀mL–1฀ ฀(4)฀ 12.02฀×฀1013฀g฀mL–1, 28. In฀a฀mole฀of฀water฀vapour฀at฀STP,฀the฀volume฀actually฀, occupied฀ or฀ taken฀ by฀ the฀ molecules฀ (i.e.,฀Avogadro’s฀, No.฀×฀volume฀of฀one฀molecule)฀is฀, (1)฀ zero, (2)฀ less฀than฀1%฀of฀22.4฀litres, (3)฀ 1%฀to฀2%฀of฀22.4฀litres, (4)฀ between฀2%฀and฀5%฀of฀22.4฀litres, 29. 2.59฀g฀of฀a฀mixture฀of฀calcium฀carbonate฀and฀magnesi­, um฀carbonate฀is฀strongly฀heated฀to฀a฀constant฀weight฀of฀, 1.3฀g.฀The฀atomic฀weights฀of฀calcium฀and฀magnesium฀, are฀40฀and฀24,฀respectively.฀State฀which฀of฀the฀follow­, ing฀weights฀expresses฀the฀weight฀of฀calcium฀carbonate฀, in฀the฀original฀mixture., (1)฀ 980฀mg฀ ฀, (2)฀ 400฀mg, (3)฀ 1.75฀mg฀฀, (4)฀ 0.84฀g, 30. Which฀of฀the฀following฀is฀a฀characteristic฀of฀both฀mix­, ture฀and฀compounds?, (1)฀ They฀contain฀components฀in฀fixed฀proportions., (2)฀ ฀Their฀ properties฀ are฀ the฀ same฀ as฀ those฀ of฀ their฀, components., (3)฀ ฀Their฀ weights฀ equal฀ the฀ sum฀ of฀ weights฀ of฀ their฀, components., (4)฀ Energy฀is฀given฀out฀when฀they฀are฀made., 31. 100฀mL฀of฀PH3฀when฀decomposes฀produces฀phospho­, rous฀and฀hydrogen.฀The฀change฀in฀volume฀is, (1)฀ 50฀mL฀ ฀, (2)฀ 500฀mL, (3)฀ 100฀mL฀ ฀, (4)฀ 150฀mL, 32. Rydberg’s฀constant฀is฀1.097373157฀×฀107฀m–1.฀It฀can฀be฀, expressed฀to฀three฀significant฀figures฀as, (1)฀ 1.0974฀×฀107฀m–1฀ (2)฀ 1.09฀×฀107฀m–1, (3)฀ 1.10฀×฀107฀m–1฀ (4)฀ 1.10฀×฀10–1, 33. The฀mass฀of฀a฀piece฀of฀paper฀is฀0.02฀g฀and฀the฀mass฀of฀, a฀ solid฀ substance฀ along฀ with฀ the฀ same฀ piece฀ of฀ paper฀, is฀20.036฀g.฀If฀the฀volume฀of฀the฀solid฀is฀2.16฀cm3,฀its฀, density฀to฀the฀proper฀number฀of฀significant฀digits฀will฀be, (1)฀ 9.27฀g฀cm–3฀, (2)฀ 9.3฀g฀cm–3, –3, (3)฀ 9.267฀g฀cm ฀, (4)฀ 43.24฀g฀cm–3, 34. On฀reduction฀with฀hydrogen฀3.6฀g฀of฀an฀oxide฀of฀metal฀, left฀3.2฀g฀of฀the฀metal.฀If฀the฀atomic฀weight฀of฀the฀metal฀, is฀64,฀the฀simplest฀formula฀of฀the฀oxide฀would฀be, (1)฀ M2O3฀ (2)฀ M2O฀, (3)฀ MO฀, (4)฀ MO2, 35. A฀metal฀oxide฀is฀reduced฀by฀heating฀it฀in฀a฀stream฀of฀, hydrogen.฀ It฀ is฀ found฀ that฀ after฀ complete฀ reduction฀, , 3.15฀ g฀ of฀ the฀ oxide฀ has฀ yielded฀ 1.05฀ g฀ of฀ the฀ metal.฀฀, We฀may฀deduce฀that, (1)฀ the฀atomic฀weight฀of฀the฀metal฀is฀8, (2)฀ the฀atomic฀weight฀of฀the฀metal฀is฀4, (3)฀ the฀atomic฀weight฀of฀the฀metal฀is฀4, (4)฀ the฀atomic฀weight฀of฀the฀metal฀is฀8, 36. When฀KClO3฀is฀heated฀to฀its฀melting฀point,฀it฀dispro­, portionates฀into฀KCl฀and฀KClO4.฀How฀many฀of฀KClO4฀, are฀formed฀on฀heating฀0.1฀mole฀of฀KClO3?, (1)฀ 01฀ ฀ (2)฀ 0.05฀ ฀ (3)฀ 0.75฀ ฀ (4)฀ 0.075, 37. 10฀litres฀of฀polluted฀air฀is฀passed฀through฀lime฀water฀so฀, that฀all฀the฀CO2฀is฀precipitated฀as฀CaCO3.฀The฀weight฀, of฀CaCO3฀formed฀is฀0.05฀g.฀What฀is฀the฀percentage฀of฀, CO2฀in฀the฀air฀sample?฀(1฀mole฀of฀gas฀under฀experi­, mental฀conditions฀has฀a฀volume฀of฀24฀litres.), (1)฀ 0.12฀ ฀ (2)฀ 1.2฀ ฀ (3)฀ 0.03฀ ฀ (4)฀ 0.6, 38. For฀complete฀oxidation฀of฀1฀mole฀of฀an฀organic฀com­, pound,฀3฀moles฀of฀oxygen฀gas฀are฀required.฀Hence,฀the฀, compound฀is฀likely฀to฀be, (1)฀ ethyne฀ ฀, (2)฀ ethanol฀, (3)฀ ethane฀ ฀, (4)฀ methanol, 39. Which฀of฀the฀following฀fertilizers฀is฀the฀richest฀nitro­, gen฀source฀on฀a฀mass฀percentage฀basis?, (1)฀ NH4NO3฀, (2)฀ (NH2)2CO, (3)฀ NH3฀, ฀, (4)฀ (NH4)2SO4, 40. The฀drug฀nicotine฀has฀the฀molecular฀formula฀C10H14N2.฀, If฀ 0.1฀ mole฀ of฀ this฀ is฀ combusted,฀ what฀ would฀ be฀ the฀, weight฀of฀CO2฀obtained?, (1)฀ 440฀g฀ (2)฀ 4.4฀g฀, (3)฀ 44฀g฀, (4)฀ 100฀g, , answers, ฀ (1)฀ 1฀, ฀ (6)฀ 4฀, (11)฀ 4฀, (16)฀ 2฀, (21)฀ 1฀, (26)฀ 1฀, (31)฀ 1฀, (36)฀ 4฀, , ฀ (2)฀ 1฀, ฀ (7)฀ 2฀, (12)฀ 3฀, (17)฀ 1฀, (22)฀ 3฀, (27)฀ 2฀, (32)฀ 3฀, (37)฀ 1฀, , ฀ (3)฀ 2฀, ฀ (8)฀ 2฀, (13)฀ 2฀, (18)฀ 1฀, (23)฀ 2฀, (28)฀ 2฀, (33)฀ 1฀, (38)฀ 2฀, , ฀ (4)฀ 1฀, ฀ (9)฀ 4฀, (14)฀ 1฀, (19)฀ 3฀, (24)฀ 3฀, (29)฀ 4฀, (34)฀ 2฀, (39)฀ 3฀, , ฀ (5)฀ 1, (10)฀ 4, (15)฀ 3, (20)฀ 4, (25)฀ 4, (30)฀ 3, (35)฀ 3, (40)฀ 3, , Statement-type Questions, In฀each฀of฀the฀following฀questions,฀a฀statement­I฀is฀given฀, followed฀by฀corresponding฀statement­II฀just฀below.฀Mark฀, the฀correct฀answer฀as฀indicated.

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Basic Concepts of Chemistry 1.19, , 1. If฀ both฀ statement­I฀ and฀ statement­II฀ are฀ true฀ and฀ the฀, statement­II฀is฀the฀correct฀explanation฀of฀statement­I., 2. If฀both฀statement­I฀and฀statement­II฀are฀true฀but฀state­, ment­II฀is฀not฀the฀correct฀explanation฀of฀statement­I., 3. If฀statement­I฀is฀true฀but฀statement­II฀is฀false., 4. If฀statement­I฀is฀false฀but฀statement­II฀is฀correct., 1. Statement-I:฀ The฀ number฀ of฀ O฀ atoms฀ in฀ 16฀ g฀ of฀฀, oxygen฀and฀16฀g฀of฀ozone฀is฀same., Statement-II: Each฀of฀the฀species฀represent฀1฀g฀atom฀, of฀oxygen., 2. Statement-I: The฀ atomic฀ masses฀ of฀ most฀ of฀ the฀, ฀elements฀are฀in฀fractions., Statement-II: The฀atomic฀mass฀represents฀the฀ratio฀of฀, the฀average฀mass฀of฀the฀atom฀to฀one฀avogram., 3. Statement-I: Molarity฀of฀pure฀water฀is฀55.5฀M., Statement-II: Molarity฀ is฀ a฀ temperature­dependent฀, parameter., 4. Statement-I: The฀ratio฀by฀volume฀of฀H2:Cl2:HCl฀in฀a฀, reaction฀H2฀+฀Cl2฀ , → ฀2HCl฀is฀1:1:2., Statement-II: Substances฀always฀react฀in฀such฀a฀way฀, that฀the฀volume฀ratio฀is฀a฀simple฀whole฀number., 5. Statement-I: 1฀Avogram฀is฀equal฀to฀10฀amu., Statement-II: 1฀amu฀is฀equal฀to฀x฀gram฀where฀x฀is฀the฀, reciprocal฀of฀Avogadro฀number., 6. Statement-I: 1฀g฀atom฀of฀iron฀represents฀the฀number฀, of฀iron฀atoms฀present฀in฀1฀g฀of฀it., Statement-II: 1฀g฀atom฀of฀element฀weight฀is฀equal฀to฀, gram฀atomic฀weight฀of฀element., , answers, ฀ (1)฀ 1฀, ฀ (6)฀ 4฀, , 8. Statement-I: 1฀mole฀of฀sulphuric฀acid฀represents฀98฀g฀, of฀the฀species., Statement-II: 1฀mole฀of฀sulphuric฀acid฀contains฀32฀g฀, each฀of฀sulphur฀and฀oxygen฀elements., 9. Statement-I: Equal฀ volumes฀ of฀ the฀ gases฀ contain฀, equal฀number฀of฀atoms., Statement-II: Atom฀ is฀ the฀ smallest฀ particle฀ which฀, takes฀part฀in฀chemical฀reactions., 10. Statement-I: Both฀ 12฀ g฀ of฀ carbon฀ and฀ 27฀ g฀ of฀ alu­, minium฀will฀have฀6.02฀×฀1023฀atoms., Statement-II: Gram฀atomic฀mass฀of฀an฀element฀con­, tains฀Avogadro฀number฀of฀atoms., , ฀ (3)฀ 2฀, ฀ (8)฀ 3฀, , ฀ (4)฀ 3฀, ฀ (9)฀ 4฀, , ฀ (5)฀ 4, (10)฀ 1, , hIntS, Multiple Choice Questions with Only One, answer, 2. Compounds฀ are฀ homogeneous฀ though฀ made฀ up฀ with฀, different฀elements., 3. Silica฀is฀a฀compound฀(SiO2)., 4. Conversion฀of฀one฀allotrope฀into฀another฀is฀a฀physical฀, change., 14. 0.128฀g฀of฀a฀combines฀with฀0.231฀g฀of฀A., 48฀g฀.................฀?, 16. M.฀Wt.฀=฀B2A3฀=฀180฀M.฀Wt.฀of฀B2A฀=฀100., 180 − 100, = 40, ฀, ∴฀At.฀Wt.฀of฀=฀, 2, 25. In฀B,฀32฀parts฀of฀x฀combines฀with฀y฀=฀84฀parts., 16฀parts฀of฀x฀will฀combine฀with฀y฀=฀42฀parts., ฀Now,฀the฀number฀of฀parts฀of฀x฀in฀both฀B฀and฀c฀is฀of฀, equal฀ different฀ masses฀ of฀ y฀ which฀ combine฀ with฀ a฀, fixed฀mass฀of฀x฀in฀B฀and฀C฀in฀the฀ratio฀3:5., Mass of y in B 3, =, ฀, Mass of y in C 5, 42 parts, 3, =, Mass of y in C 5, , 7. Statement-I: The฀formula฀of฀calcium฀carbide฀is฀CaC2., Statement-II: 1฀ mole฀ of฀ calcium฀ carbide฀ contains฀ 2฀, moles฀of฀carbon฀atoms., , ฀ (2)฀ 1฀, ฀ (7)฀ 2฀, , ฀, , 5, Mass฀of฀y฀in฀C฀=฀ × 42 = 70 parts, 3, , 27. M.฀Wt.฀of฀sucrose฀=฀342, → ฀12C฀+฀11H2O, C12H22O11฀ ∆, No.฀of฀molecules฀lost฀on฀heating฀0.684฀=฀, ฀, , 0.684 × 11× 6 ×10 23, ฀=฀1.32฀×฀1022, 342, , 35. Gram฀atomic฀mass฀of฀Cu฀=฀63.5, 0.635, No.฀of฀moles฀of฀0.635฀of฀Cu฀=฀, = 0.01, 63.5, No.฀of฀Cu฀atoms฀in฀one฀mole฀=฀6.02฀×฀1023, No.฀of฀Cu฀atoms฀in฀0.01฀mole฀=฀0.01฀×฀6.02฀×฀1023, ฀, ฀, ฀, ฀ ฀ ฀ ฀ ฀ ฀฀, =฀6.02฀×฀1021

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1.20 Objective Chemistry - Vol. I, , 36. Mol.฀Wt.฀of฀CH4฀=฀16, No.฀of฀moles฀in฀1.6฀g฀=฀0.1, No.฀of฀molecules฀in฀1.6฀g฀=฀0.1฀×฀6฀×฀1023, Each฀molecule฀contains฀6฀+฀4฀=฀10฀electrons, No.฀of฀electrons฀present฀in฀1.6฀g฀฀=฀0.1฀×฀6฀×฀1023฀×฀10฀, =฀6฀×฀1023, , 44, =฀1฀mole, 44, So,฀N2O฀contains฀more฀number฀of฀molecules, Number฀of฀moles฀of฀N2O฀=฀, , 52. (1)฀ 2M฀K2SO4฀gives฀6M฀ions฀(2M฀K+฀and฀1M฀SO42–), ฀, ฀3M฀Na2CO3฀gives฀9M฀ions฀(6M฀K+฀and฀3M฀CO32–), ฀, Total฀15M, (2)฀ ฀2M฀ NaCl฀ gives฀ 4M฀ ions฀ (2M฀ Na+฀ 2MCl–)฀ and฀฀, 2M฀ KCl฀ also฀ gives฀ 4M฀ ions฀ (2M฀ K+฀ 2MCl–).฀฀, Total฀3M., (3)฀ ฀2M฀ MnSO4฀ gives฀ 2M฀ Mn2+฀ and฀ 2M฀ SO42–฀ ions฀, and฀3M฀K2SO4฀gives฀6M฀K+฀and฀3M฀SO42–฀ions.฀, Total฀10M., (4)฀ ฀2M฀K2SO4฀gives฀4M฀K+฀ions฀2M฀SO42–฀ions฀and฀, 2M฀(NH4)SO4฀gives฀4M฀NH4+฀and฀2M฀SO42–฀ions.฀, Total฀12N., ฀, ฀2M฀ NaCl฀ and฀ 2M฀ KCl฀ mixture฀ contains฀ less฀, ฀number฀of฀ions., , 37. No.฀of฀rupees฀spent฀in฀one฀second฀=฀106, No.฀of฀spent฀in฀1฀year฀=฀106฀×฀60฀×฀60฀×฀24฀×฀365, Avogadro฀number฀rupees฀will฀be฀spent฀in, 6.02 × 10 23, = 19.089 × 109 years, 10 × 60 × 60 × 24 × 365, 6, , 43. The฀volume฀of฀6฀×฀1023฀molecules฀of฀water฀is฀18฀cc., 18, The฀volume฀of฀1฀molecule฀=฀, = 3 × 10 −23 cc, 6.023 × 10 23, 44. 100฀ g฀ of฀ haemoglobin฀ contains฀ 0.33฀ g฀ of฀ iron฀ and฀, 67200฀g฀of฀haemoglobin฀contains, 67200 1, × = 224, 100 3, 224, =4, No.฀of฀iron฀atoms฀=฀, 56, 45. Each฀molecule฀of฀CH3COOH฀contains฀two฀atoms฀of฀C,฀, 2฀atoms฀of฀O2฀and฀4฀atoms฀of฀H2., ฀So,฀ one฀ mole฀ of฀ CH3COOH฀ contains฀ 2฀ moles฀ of฀ C฀฀, atoms,฀4฀moles฀of฀H฀atoms฀and฀2฀moles฀of฀O฀atoms., 47. (1)฀ 16฀g฀of฀O2฀is฀0.5฀mole฀and฀14฀g฀of฀N2฀is฀0.5฀mole, (2)฀ 8฀g฀of฀0.25฀mole฀and฀22฀g฀of฀CO2฀is฀0.5฀mole, (3)฀ 28฀g฀of฀N2฀is฀1฀mole฀and฀22฀g฀of฀CO2฀is฀0.5฀mole, (4)฀ 32฀g฀of฀is฀1฀mole฀and฀32฀g฀of฀N2฀is฀1.143฀mole, ฀, ฀So,฀16฀g฀of฀O2฀and฀14฀g฀of฀N2฀contain฀the฀same฀, number฀of฀molecules., 48. Each฀molecule฀of฀glucose฀(C6H12O6)฀contains฀6฀carbon฀, atoms฀and฀9฀g฀of฀glucose฀contain฀, 9, × 6.023 × 10 23, 180, =฀฀3.0115฀×฀1022฀glucose฀molecules฀or฀฀, 6฀×฀3.0115฀×฀1022, =฀1.8069฀×฀1023฀carbon฀atoms, 49. The฀weight฀of฀ 6.023 × 10 23 ฀atoms฀of฀zinc฀is฀65.49, The฀weight฀of฀ 6.023 × 10 21 ฀atoms฀of฀zinc฀is฀0.654฀g, 50. AlCl3฀ionises฀giving฀4฀ions฀(AlCl3฀ , → ฀Al3+฀+฀3Cl−), So,฀0.1฀mole฀of฀AlCl3฀gives฀ 4 × 6.023 × 10 22 ฀ions, 51. Let฀the฀weight฀of฀NO2฀and฀N2O฀is฀44฀gm., ฀Number฀of฀moles฀of฀NO2฀=฀, , 44, ฀=฀0.9565฀mole, 46, , 53. 100฀g฀of฀caffeine฀contains฀28.9฀g฀of฀N2., 194฀g฀of฀caffeine฀contains฀, , 194 × 28.9, = 56 g, 100, , 56, =4, 14, 54. The฀cost฀of฀1000฀g฀of฀sugar฀is฀Rs.฀10., 342 × 10, The฀cost฀of฀1฀mole฀or฀342฀g฀of฀sugar฀is฀, = 3.42, 1000, No.฀of฀nitrogen฀atoms฀in฀caffeine฀=฀, , 55. Each฀ molecule฀ of฀ sulphuric฀ acid฀ (H2SO4)฀ contains฀, 1฀ sulphur฀ atom.฀ So,฀ 0.5฀ mole฀ of฀ sulphuric฀ acid฀ con­, tains฀0.5฀gram฀atom฀of฀sulphur., 342 × 10, = 3.42, 1000, 56. ∴฀Vapour฀density฀of฀A฀is฀4฀times฀that฀of฀B.฀Hence,฀the฀, molecular฀weight฀of฀A฀must฀be฀4฀times฀that฀of฀B., ฀, , 57. Since฀VD฀of฀the฀substance฀is฀4฀times฀that฀of฀methane,฀the฀, M.W.฀of฀the฀substance฀must฀also฀be฀4฀times฀that฀of฀CH4., 58. Ratio฀of฀the฀elements, 40 60 5 5, : or : ฀∴฀The฀empirical฀formula฀=฀MO, 16 24 2 2, 59., , 60., , 24 4 32, : :, = 2 : 4 : 2 ฀∴฀The฀empirical฀formula฀=฀CH2O, 12 1 16, 38.8 16 45.2, =, : :, 3=, .23 : 16 : 3.22 1 : 5 : 1, 12 1 14, ฀The฀empirical฀formula฀of฀the฀compound฀is฀CH5N.฀The฀, compound฀is฀CH3NH2.

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Basic Concepts of Chemistry 1.21, , 61. 0.032฀g฀of฀S฀present฀in฀100, 2 × 32 × 100, = 2, 00, 000, 232฀g฀of฀S฀present฀in฀, 0.032, 63. Minimum฀ molecular฀ mass฀ must฀ contain฀ at฀ least฀ one฀฀, S฀atom., 32 × 100, = 941, 0.34, 64., , 85.45 14.55, :, = 7.12 : 14.55 or 1 : 2, 12, 1, , So,฀the฀empirical฀formula฀is฀CH2., For฀C2H6,฀the฀empirical฀formula฀should฀be฀CH3., 65. VD฀of฀air฀is฀weight฀of฀11200฀cc฀or฀11.2฀litres, 0.001293 × 11.2 = 0.143, 62. Let฀the฀formula฀of฀hydrocarbon฀is฀CxHy., y, y, , CxHy฀+฀  x +  ฀O2฀ , → ฀xCO2฀+฀ ฀H2O, 4, 2, , y, 1฀mole฀ x + ฀moles฀฀ x฀moles, 4, 15฀ml฀฀, 45฀moles฀฀, 30฀ml฀, 13฀ ฀, 2, y, y, = 3 = 3 − 2 (∴ x = 2) or y = 4, 4, 4, Hence,฀the฀formula฀of฀hydrocarbon฀=฀C2H4, ∴x = 2x +, , 66. According฀to฀the฀reaction, → ฀CO2฀+฀N2฀+฀3H2O, NH2CONH2฀+฀2HNO2฀ , 60฀g฀of฀urea฀gives฀222,400฀cc฀of฀N2฀at฀STP, 0.120฀g฀of฀urea฀gives, 0.12 × 22400 × 2, = 89.6 cc, 60, → CO2฀+฀2H2O, 67. CH4฀+฀2O2฀ , ฀22.4฀litres฀of฀methane฀at฀STP฀on฀burning฀give฀218฀g฀, of฀water., 1฀litre฀of฀methane฀at฀STP฀on฀burning฀gives, ฀, , 1.0 × 2 × 18, g of water, 22.4, , 68. Na2CO3฀+฀2HCl฀ , → 2NaCl฀+฀H2O฀+฀CO2, 2฀moles฀of฀HCl฀react฀with฀1฀mole฀of฀Na2CO3, 0.1฀mole฀of฀HCl฀reacts฀with฀0.05฀mole฀of฀Na2CO3, ∴฀0.05฀mole฀of฀Na2CO3฀=฀0.05฀106฀=฀5.3฀g, → ฀AgCl฀+฀NaNO3, 69. NaCl฀+฀AgNO3฀ , 1฀mole฀of฀NaCl฀reacts฀with฀1฀mole฀of฀AgNO3., 250฀ml฀of฀0.1฀M฀AgNO3฀=฀0.025฀mole, 400฀ml฀of฀0.1฀M฀NaCl฀=฀0.04฀mole, ฀∴฀0.025฀mole฀of฀AgNO3฀can฀react฀with฀0.025฀mole฀of฀, NaCl฀forming฀0.025฀mole฀of฀AgNO3., , 70. Na2CO3฀+฀2HCl฀ , → ฀2NaCl฀+฀H2O฀+฀CO2, Applying฀, , V1 M1 V2 M 2, 0.55 × 0.1 V2 × 0.1, =, =฀, =, n1, n2, 1, 2, ฀ ฀ ฀฀V2฀=฀1.1฀litre, , 71. CaCO3฀ , → ฀CaO฀฀฀฀+฀฀฀฀CO2, 100฀g฀, 56฀g฀฀฀฀฀฀฀฀฀฀฀44฀g, ฀56฀ g฀ of฀ CaO฀ is฀ obtained฀ from฀ 100฀ g฀ of฀ CaCO3฀ and฀, 56฀kg฀of฀CaO฀will฀be฀obtained฀from฀100฀kg฀of฀CaCO3., → ฀MgCl2฀+฀H2, 72. Mg฀+฀2HCl฀ , 1฀ ฀g฀atom฀of฀Mg฀liberates฀1฀mole฀of฀H2฀from฀acid฀and฀฀, 12฀ g฀ of฀ Mg฀ or฀ 0.5฀ g฀ atom฀ of฀ Mg฀ liberates฀ 0.5฀ mole฀฀, of฀H2., → ฀CaCl2฀+฀H2O฀+฀CO2, 73. CaCO3฀+฀2HCl฀ , 100฀g฀of฀CaCO3฀gives฀22.4฀litres฀of฀CO2฀at฀STP, 50฀g฀of฀CaCO3฀gives฀11.2฀litres฀of฀CO2฀at฀STP, → ฀C6H5CH2CH3, 74. C6H5CH฀=฀CH2฀+฀H2฀ Pt, ฀one฀mole฀of฀phenyl฀ethylene฀combines฀with฀1฀mole฀of฀, H2,฀i.e.,฀22.4฀litres฀of฀H2฀at฀STP, → CO2฀+฀2H2O, 75. CH4฀+฀2O2฀ , 1฀vol฀฀฀2฀vol, 5฀cc฀of฀methane฀requires฀10฀cc฀of฀O2, → ฀2CO2฀+฀2H2O, C2H4฀+฀3O2฀ , 1฀vol฀฀฀฀฀3฀vol, 5฀cc฀of฀C2H4฀requires฀15฀cc฀of฀O2, ∴฀Total฀volume฀of฀O2฀required฀is฀10฀+฀15฀=฀25฀cc, 76. 100฀g฀of฀coal฀contain฀1฀g฀of฀sulphur., 2 × 106 × 1000 g of coal contains, 2 × 106 × 1000, = 2 × 10 7 g of sulphur, 100, S, ฀ ulphur฀on฀burning฀gives฀SO2฀according฀to฀the฀equation฀, S฀+฀O2฀ , → ฀SO2, 32฀g฀of฀sulphur฀gives฀64฀g฀of฀SO2, 2 × 10 7 g ฀of฀sulphur฀gives฀, 2 × 10 7 × 64, = 4 × 10 7 g, 32, or฀ 4 × 10 4 kgSO2, 77. Follow฀the฀above฀question฀(76), 2, 16000 ×, 64, 78. The฀ amount฀ of฀ product฀ to฀ be฀ obtained฀ according฀ to฀, a฀ chemical฀ reaction฀ is฀ called฀ theoretical฀ yield฀ of฀ the฀, ฀reaction.

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1.22 Objective Chemistry - Vol. I, , → ฀2CO2, 79. 2CO฀+฀O2฀ , ฀According฀ to฀ the฀ equation,฀ 56฀ g฀ of฀ CO฀ gives฀ 88฀ g฀฀, of฀CO2., So,฀5.6฀g฀of฀CO฀gives฀8.8฀g฀of฀CO2., → ฀12CO2฀+฀11H2O, 80. C12H22O11฀+฀12O2฀ , 1฀mole฀of฀lactose฀gives฀12฀moles฀of฀CO2., 1, ∴฀ ฀mole฀of฀lactose฀gives฀1฀mole฀of฀44฀g฀of฀CO2., 12, 81. Cl2O7฀decomposes฀according฀to฀the฀equation:, 2Cl2O7฀ , → ฀2Cl2฀+฀7O2, The฀ratio฀of฀Cl2:O2฀is฀2:7฀or฀1:3.5., 82. Since฀all฀the฀ethylene฀molecules฀in฀100฀g฀polymerises,฀, the฀polyethylene฀formed฀will฀be฀100฀g., → ฀FeCl2฀+฀H2, 83. Fe฀+฀2HCl฀ , 2฀moles฀of฀HCl฀will฀produce฀1฀mole฀of฀Fe2+฀ions., 50, × 4 = 0.2 mole, 1000, ∴฀No.฀of฀Fe2+฀ions฀formed฀is฀0.1฀mole., Numbers฀of฀moles฀present฀in฀HCl฀=, , → ฀2CO, 84. 2C฀฀+฀฀O2฀ , 24฀ 32, ฀Since฀24฀g฀of฀carbon฀can฀react฀only฀with฀32฀g฀of฀oxy­, gen,฀the฀excess฀oxygen฀will฀be฀left฀over.฀Thus,฀carbon฀, is฀the฀limiting฀reagent., 85. A฀+฀2B฀ , → ฀C, ฀1฀ mole฀ of฀ A฀ reacts฀ with฀ 2฀ moles฀ of฀ B฀ to฀ produce฀, 1฀mole฀of฀C., ∴฀8฀moles฀of฀B฀can฀react฀with฀4฀moles฀of฀A฀to฀produce฀, 4฀moles฀of฀C., 86. The฀reaction฀shows฀that฀2฀moles฀of฀Al฀react฀with฀moles฀, of฀O2฀to฀produce฀1฀mole฀of฀Al2O3., 87. Mol.฀wt.฀of฀x฀=฀12.01฀+฀(2฀×฀16)฀=฀44.01฀g, 88. CH4฀+฀2O2฀ , → ฀CO2฀+฀2H2O, ฀20฀mL฀of฀O2฀can฀oxidise฀only฀10฀mL฀of฀CH4฀to฀pro­, duce฀10฀mL฀of฀CO2฀and฀20mL฀of฀H2O(g).฀But฀when฀, cooled฀to฀room฀temperature,฀H2O(g)฀becomes฀H2O฀(l)฀, and฀ its฀ volume฀ is฀ negligible.฀ So,฀ after฀ explosion฀ the฀, reaction฀mixture฀contains฀10฀mL฀of฀CH4฀and฀10฀mL฀of฀, CO2฀(a฀total฀of฀20฀mL)., , 2H2฀+฀O2฀ , → ฀2H2O, 32฀g฀of฀O2฀can฀combine฀with฀4฀g฀of฀H2, 9.6฀g฀of฀O2฀can฀combine฀with฀1.2฀g฀of฀H2, → ฀MgCl2฀+฀H2, Mg฀+฀2HCl฀ , 2฀g฀of฀H2฀can฀be฀liberated฀by฀24฀g฀of฀Mg, 1.2฀g฀of฀H2฀can฀be฀liberated฀by฀14.4฀g฀of฀Mg, → ฀CO2, 91. C฀+฀O2฀ , 12฀g฀of฀carbon฀gives฀22.4฀litres฀of฀CO2, ∴฀11.2฀litres฀of฀CO2฀is฀given฀by฀6฀g฀of฀C, The฀unburnt฀carbon฀is฀10฀–฀6฀=฀4฀g, → ฀MnCl2฀+฀2H2O฀+฀Cl2, 92. MnO2฀+฀4HCl฀ , ฀22.4฀litres฀of฀Cl2฀at฀STP฀can฀be฀produced฀by฀87฀g฀of฀, MnO2, 1.78฀litres฀of฀Cl2฀at฀STP฀can฀be฀produced฀by, 1.78 × 87, = 6.905 g, 22.4, → ฀K2CO3฀+฀H2O฀+฀CO2, 93. 2KHCO3฀ , 200฀g฀of฀KHCO3฀gives฀residue฀of฀138฀g฀of฀K2CO3, 1, 1, 1, ฀∴ KHCO3 → K 2 CO3 + H 2 O + CO2, 2, 2, 2, 94. In฀100฀g฀of฀chlorophyll,฀the฀quantitiy฀of฀Mg฀is฀2.68฀g., In฀2฀g฀of฀chlorophyll,฀the฀quantity฀of฀, 2 × 2.68, Mg฀=฀, = 0.0536 g, 100, 24฀g฀of฀Mg฀contain฀6฀×฀1023฀atoms, ∴฀0.0536฀g฀of฀Mg฀contains฀=฀, 0.0536 × 6 × 10 23, = 1.34 × 10 21 atoms, 24, 95. K2SO4฀ , → ฀2K+฀+฀SO42–, ฀Since฀ 1฀ mole฀ of฀ K2SO4฀ gives฀ 2฀ moles฀ of฀ K+฀ ions฀ on฀, diluting฀100฀ml฀of฀0.2฀M฀K2SO4฀with฀100฀ml฀of฀water,฀the฀, concentration฀of฀K+฀ions฀in฀the฀solution฀becomes฀0.2฀M., , Practice exercise Level-I, 1., , 2.65 × 10 22, = 0.0442 mole, 6 × 10 23, 0.0887 0.0442 0.132, Mole ratio =, :, :, ฀=฀2:1:3, 0.0442 0.0442 0.0442, ∴฀The฀empirical฀formula฀=฀Na2CO3, , 89. 2KClO3฀ , → ฀2KCl฀+฀3O2, → ฀12CO2฀+฀11H2O, C12H22O11฀+฀12O2฀ , ∴฀moles฀of฀KClO3฀required฀=฀8, , 2. Ratio฀ of฀ the฀ atoms฀ is฀ 1:2.฀ So,฀ the฀ empirical฀ formula฀฀, is฀CrO2., , 90. 2KClO3฀ , → ฀2KCl฀+฀3O2, 245฀g฀of฀KClO3฀gives฀96฀g฀of฀O2, 24.5฀g฀of฀KClO3฀can฀give฀9.6฀g฀of฀O2, , 3. Gram฀at.฀Wt.฀= 6.644 × 10 −23 × 6 × 10 23 = 40, 40 × 1000, No.฀of฀gram฀atoms฀=฀, = 40, 40

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Basic Concepts of Chemistry 1.23, , 4. Oleum฀is฀H2S2O7.฀Atomicity฀=11., → ฀2H2฀+฀O2, 5. 2H2O฀ , ฀36฀g฀of฀water฀gives฀67.2฀litres฀of฀H2฀and฀O2฀mixture฀, and฀16.8฀litres฀of฀H2฀and฀O2฀mixture฀is฀obtained฀from, ฀, , 16.8 × 36, = 9 gm of H 2O, 67, , 6. 3.2฀of฀salt฀lost฀1.8฀g฀of฀H2O, 160฀g฀loses฀90฀g฀of฀H2O฀and฀5฀moles฀of฀H2O, 7. 0.3฀mole฀฀gives฀26.4฀g฀of฀CO2, 1฀mole฀gives฀88฀g฀of฀CO2, So,฀the฀hydrocarbon฀contains฀2฀carbon฀atoms., ฀Since฀ it฀ decolourises฀ Bayer’s฀ reagent฀ and฀ gives฀, ฀precipitate฀(with฀Tollen’s฀reagent฀it฀should฀be฀alkyne.฀, Hence,฀the฀hydrocarbon฀is฀C2H2., 50 50, :, = 3:2, 20 30, ฀Since฀ the฀ compound฀ contains฀ 6฀ atoms฀ of฀ A,฀ the฀฀, formula฀is฀A6B4., , 8. Ratio฀of฀atoms฀, , 0.32, = 0.01, 32, ฀Therefore,฀the฀moles฀of฀compound฀x฀is฀also฀0.1฀Mol.฀, Wt.฀of฀x฀=฀26.฀Molecular฀formula฀=฀C2H2., , 9. Moles฀of฀O2฀=฀, , 10. Iodine฀present฀in฀2.5฀is฀0.025฀gm., 167฀g฀of฀KI฀contain฀6฀×฀1023฀iodide฀ions, 0.025฀g฀of฀KI฀­­­­฀?, 0.025 × 6 × 10 23, = 9.03 × 1019, 167, 11. 0.6฀mole฀of฀chloride฀ion฀=฀0.3฀mole฀of฀MgCl2, 0.2฀mole฀of฀sulphate฀ion฀=฀0.2฀mole฀of฀MgSO4, 12. (NH4)3PO4฀contains฀12฀moles฀of฀H฀atoms฀and฀4฀moles฀, of฀O฀atoms.฀So,, 3.18฀moles฀of฀H฀atoms฀is฀equal฀to฀1.06฀atom฀of฀O., , → ฀2AlCl3฀+฀3H2, 17. 2Al฀+฀6HCl฀ , 2฀moles, → ฀KCl฀+฀H2O, 18. HCl฀+฀฀KOH฀ , 0.2M฀฀฀฀0.4M฀฀฀฀฀฀฀฀฀฀฀฀฀0.2M, ฀HCl฀completely฀reacts฀0.2M฀KOH฀left,฀0.2M฀KCl฀are฀, formed.฀Since฀the฀volume฀is฀doubled฀the฀solution฀con­, tains฀0.2M฀K+,฀0.1M฀OH–฀and฀0.1฀MCl–., 19. 0.05฀M฀Cu฀is฀present฀in฀100฀mL., No.฀of฀moles฀=฀, , 0.05 × 100, 1, =, 1000, 200, , 20. 111฀g฀of฀iron฀combines฀with฀48฀g฀of฀O2฀in฀Fe2O3฀and฀, 2.79฀g฀of฀iron฀combines฀with฀1.2฀g., 69.5 30.5, 21. = =, 16, 14, 4.34:2.17฀⇒ 4:2, The฀formula฀is฀N2O4., 22. 2NaOH฀+฀CO2฀ , → ฀Na2CO3฀+฀H2O, 80฀, 1฀mole, The฀No.฀of฀moles฀of฀CO2฀in฀the฀mixture฀is฀0.25., ฀Since฀it฀reacts฀with฀only฀20฀g฀of฀NaOH.฀So,฀the฀No.฀, of฀moles฀of฀CO฀is฀0.75.฀It฀is฀converted฀into฀CO2฀and฀, requires฀60฀g฀of฀NaOH฀for฀the฀same., 25. CuSO4฀.฀5H2O฀contains฀64฀g฀of฀Cu฀and฀144฀g฀of฀oxygen., ฀∴฀The฀CuSO4฀⋅ 5H2O฀containing฀3.2฀g฀of฀Cu฀have฀7.2฀g฀, of฀oxygen., 26. CaCO3฀ , → ฀CaO฀+฀CO2, 1฀mole฀of฀CaCO3฀gives฀1฀mole฀of฀CO2, 10฀g฀of฀CaCO3฀=฀0.1฀mole฀of฀CaCO3, 0.1฀mole฀of฀CaCO3฀gives฀0.1฀mole฀of฀CO2, → ฀2NaHCO3, Na2CO3฀+฀H2O฀+฀CO2฀ , 1฀mole฀of฀CO2฀gives฀2฀moles฀of฀NaHCO3, ∴฀0.1฀mole฀of฀CO2฀gives฀0.2฀moles฀of฀NaHCO3., , 14. The฀oxygen฀present฀in฀1฀litre฀of฀air฀is฀0.21฀litre฀of฀O2., 0.21, ∴฀No.฀of฀moles฀of฀O2฀=฀, = 0.0093 mole, 22.4, , 27. All฀the฀molecules฀contain฀the฀same฀number฀of฀oxygen฀, atoms.฀The฀more฀the฀molecular฀weight,฀the฀lesser฀the฀, weight฀of฀oxygen., , → ฀Pb(IO3)2฀+฀2KNO3, 15. Pb(NO3)2฀+฀2KIO3฀ , 1฀mole฀ ฀ 2฀moles, ฀0.฀ M฀ of฀ KIO3฀ reacts฀ with฀ 0.5฀ mole฀ of฀ Pb(NO3)2.฀ So฀฀, 0.3฀ mol฀ of฀ Pb(NO3)2฀ left฀ behind฀ and฀ 0.5฀ mol฀ of฀, Pb(IO3)2฀is฀formed.฀Hence฀the฀ratio฀is฀5/3., , → ฀MgO฀+฀CO2, 28. MgCO3฀ , 84฀g฀=฀1฀mole฀, ∴฀10฀g฀of฀MgCO3฀contain฀8.4฀g, Hence,฀per฀cent฀purity฀of฀MgCO3฀=฀84., , 16. Limiting฀reagent฀is฀Ba(OH)2.฀For฀one฀mole฀of฀Ba(OH)2฀, two฀moles฀of฀water฀are฀formed.฀So,฀from฀0.1฀mole฀of฀, Ba(OH)2,฀0.2฀mole฀of฀water฀is฀formed., , 29. Follow฀the฀above฀question฀(28)., 30. CO2฀contains฀22฀protons.฀So,฀z–฀contains฀21,฀x+฀con­, tains฀25฀and฀y2+฀contains฀24฀electrons.

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1.24 Objective Chemistry - Vol. I, , 31. According฀to฀the฀equation,฀60฀g฀of฀urea฀react฀with฀80฀g฀, of฀NaOH฀giving฀34฀g฀of฀ammonia.฀So,฀6฀g฀of฀urea฀can฀, give฀3.4฀g฀of฀NH3.฀But฀the฀per฀cent฀yield฀is฀only฀80%., 3.4 × 80, = 2.72 g, 100, , 46. The฀ratio฀of฀C,฀H฀and฀N฀is฀9:1:3.5, 9 1 3.5, : :, or 0.75 :1 : 0.25 or 3 : 4 : 1, ฀, 12 1 14, ∴฀The฀empirical฀formula฀is฀C3H4N., , 32. No.฀of฀carbon฀atoms฀in฀cortisone฀=฀21, Wt.฀of฀21฀C฀atoms฀=฀21฀×฀12฀=฀252, 69.98฀g฀of฀carbon฀in฀100฀g฀of฀cortisone, 252฀g฀of฀carbon฀contain฀in, 252 × 100, = 360.1, 69.98, , Practice exercise Level-II, , → ฀BaSO4฀+฀2HF, 33. BaF2฀+฀H2SO4฀ , 2NaOH฀+฀H2SO4฀ , → ฀Na2SO4฀+฀2H2O, ฀1฀ mole฀ of฀ H2SO4฀ reacts฀ with฀ BaF2฀ and฀ produces฀ 2฀, moles฀of฀HF.฀To฀react฀with฀2฀moles฀of฀HF฀the฀NaOH฀, required฀is฀2฀moles฀and฀to฀react฀with฀1฀mole฀of฀H2SO4฀, left฀required฀2฀moles฀of฀NaOH.฀Thus,฀a฀total฀of฀4฀moles฀, of฀NaOH฀is฀required., 35. Since฀ the฀ gram฀ atomic฀ weight฀ of฀ Al฀ is฀ less,฀ more฀, amounts฀can฀be฀obtained฀for฀the฀same฀rate., 1.24, Moles฀of฀P฀=฀, = 0.04, 31, 0.96, = 0.03, Moles฀of฀S฀=฀, 32, Ratio฀of฀moles฀of฀P:S฀=฀0.04:0.03฀=฀4:3., ∴฀Empirical฀formula฀=฀P4S3., 38. For฀ precipitating฀ 0.2฀ moles฀ of฀ BaSO4,฀ 0.2฀ moles฀ of฀, H2SO4฀and฀to฀precipitate฀0.1฀mole฀of฀PbCl2,฀0.2฀mole฀, of฀ HCl฀ are฀ required.฀ These฀ can฀ be฀ obtained฀ from฀฀, 0.1฀mole฀of฀S2Cl2., → ฀C2H2฀+฀6AgI, 41. 2HCI3฀+฀6Ag฀ , 2฀moles฀of฀CHI3฀gives฀1฀mole฀of฀C2H2, ฀0.01฀ mole฀ of฀ CHI3฀ gives฀ 0.005฀ mole฀ of฀ C2H5฀ that฀, occupies., 42. The฀mole฀ratio฀of฀oxygen฀that฀combines฀with฀1฀mole฀, of฀manganese฀in฀MnO2,฀Mn2O3,฀MnO3฀and฀Mn2O7฀is฀, 2:1.5:3:3.5.฀So,฀Mn2O7฀contains฀maximum฀percentage฀, by฀weight฀of฀combined฀oxygen., 43. The฀mole฀ratio฀of฀oxygen฀that฀combines฀with฀1฀mole฀of฀, iron฀in฀FeO,฀Fe2O3฀and฀Fe3O4฀is฀1:1.5:1.33,฀respective­, ly.฀Therefore,฀the฀amount฀of฀O2฀required฀is฀maximum฀, for฀the฀formation฀of฀Fe2O3., 254 80, :, = 2 : 5.฀So,฀the฀compound฀is฀I2O5., 44., 127 16, 45. Since฀the฀metal฀ion฀is฀M2+฀and฀phosphate฀is฀PO43–฀the฀, formula฀of฀metal฀phosphate฀would฀be฀M3(PO4)2., , 1. NH4Cl฀ ∆, → ฀NH3฀+฀HCl, ฀Since฀one฀mole฀of฀NH4Cl฀is฀giving฀two฀moles฀of฀gase­, ous฀NH3฀and฀HCl,฀vapour฀density฀becomes฀half., 2. Clay฀contains฀x%฀silica,฀81฀–฀฀x%฀impurities,฀19%฀H, ฀, 2O.฀, After฀ partial฀ drying฀ 50%฀ silica,฀ 40%฀ impurities฀ and฀, 10%฀H2O฀are฀obtained., x 81 − x, =, So,฀, 50, 40, x฀=฀45%, 3. Moles฀of฀C2O42–฀=฀0.02, No.฀of฀ions฀=฀0.02฀×฀6.02฀×฀1023฀=฀1.204฀×฀1022, → ฀A2Ox฀+฀XCO2, 4. A2(CO3)x฀ , → ฀B2Oy฀+฀yCO2, B2(CO3)y฀ , 5. 120฀g฀MgSO4฀contains฀18x฀g฀of฀H2O, 87฀g฀of฀MgSO4฀contains฀13฀g฀of฀H2O, 120 18 x, =, 87, 13, ∴ x฀=฀1., 6. 7฀g฀of฀sodium฀combines฀with฀93฀g฀of฀anion฀present฀in฀, the฀sodium฀salt฀of฀dye., 23 × 93, ฀g฀of฀anion, 23฀g฀of฀sodium฀react฀with฀, 7, Mol.฀wt.฀of฀acid฀dye฀=฀1฀+฀305.5฀=฀306.5, 7. 8.4฀g฀of฀x฀combines฀with฀6.5฀g฀of฀oxygen., ฀96฀ g฀ of฀ oxygen฀ combines฀ with฀, x g฀of฀x, , 96 × 8.4, = 124 g of ฀, 6.5, , 124, = 31., 4, 14. Initial฀no.฀of฀moles฀of฀CO2฀, ∴฀At.฀Wt.฀=฀, , =, , 200 × 10 −3, = 4.545 × 10 −3, 44, , No.฀of฀moles฀of฀CO2฀removed฀=฀1.66 × 10 −3, No.฀of฀CO2฀moles฀remained฀=฀ 2.88 × 10 −3, 17. 100฀g฀of฀crystals฀contain฀zinc฀=฀22.65฀g, 22.65, 20฀g฀of฀crystals฀contain฀zinc฀ =, × 20 = 4.53 g, 100

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Basic Concepts of Chemistry 1.25, , 21. Compound฀ Composition, ฀, A฀, 40%฀x;฀60%฀y, ฀, B฀, 25%฀x;฀75%฀x, In฀compound฀A,฀40฀g฀of฀x฀combine฀with฀60฀g฀of฀y., In฀compound฀B,฀25฀g฀of฀x฀combine฀with฀y฀=฀75฀g, 75, 40฀g฀of฀x฀combine฀with฀y฀ = × 40 = 120 g, 25, ฀Ratio฀between฀the฀weight฀of฀y฀which฀combine฀with฀the฀, fixed฀weight฀of฀x฀(40฀g)฀=฀60:120฀=1:2., 22. Let฀the฀mass฀of฀each฀substance฀is฀32฀a., Then.฀mole฀ratio฀is฀, 32, 32, 32, O2 = ; H 2 =, and CH 4 =, ฀, 32, 2, 2, ∴฀The฀volume฀ratio฀is฀also฀1:16:2, 25. 3F–;฀1฀Formula฀unit฀AlF3, 3.0 × 10 24 F − = 1× 10 24 ฀formula฀units., ฀, 26. Mol.฀mass฀of฀Fe(HCOO)2฀=฀170, Fe฀in฀100฀mg฀of฀Fe(HCOO)2฀, 56 × 100, ฀, =, = 32.9 mg, 170, Total฀Fe฀in฀400฀mg฀capsule฀=฀32.9฀mg, 32.9 × 100, = 8.2, ∴฀%฀of฀Fe฀in฀capsule฀=฀, 400, 27. Since฀almost฀whole฀the฀mass฀of฀an฀atom฀is฀in฀the฀nucleus, Mass฀of฀F฀nucleus฀=฀Mass฀of฀F฀atom, 19, g, ฀, ฀, ฀ ฀ =, 6.02 × 10 23, ฀, ฀, ฀ ฀ = 3.15 × 10 −23 g, (At.฀mass฀of฀F฀=฀19), 4, Volume฀of฀nucleus฀ = π r 3, 3, 4 22, ฀, = × × (5 × 10 −13 )3 cm3, 3 7, ฀, ฀, ฀, , = 5.24 × 10 −37 cm3, Density฀=฀, , 3.15 × 10 −23 g, Mass, =, Volume 5.24 × 10 −37 cm3, , = 6.02 × 1013 g cm − 3 = 6.02 × 1013 g / mL., , 28. We฀suppose฀that฀ at฀4°C฀(when฀ it฀has฀maximum฀ den­, sity)฀there฀is฀no฀empty฀space฀between฀the฀molecules฀of฀, water฀=฀18฀mL, Vol.฀of฀1฀mole฀of฀water฀vapour฀at฀STP฀=฀22400฀mL, Percentage฀฀of฀฀Volume฀occupied฀= 18 × 100 = 0.08%, 22400, , The฀volume฀actually฀occupied฀is฀less฀than฀1%., , 29. Let฀the฀weight฀of฀CaCO3฀=฀xg, ฀, CaCO3฀ , → ฀CaO฀+฀CO2, → ฀Mgo฀+฀CO2, ฀, MgCO3฀ , ฀, Weight฀of฀CaO฀+฀MgO฀=฀1.3฀g, ฀, ฀, , 56, 40, × x + (259 − x ), = 1.3 g, 100, 84, x฀=฀0.84฀g., ∴, , 31. 2PH3฀ , → ฀2P฀+฀3H2, ฀, 2฀moles฀ ฀, 3฀moles, ฀, 100฀mL฀ ฀, 150฀mL, ฀, Increase฀in฀volume฀=฀150฀฀฀100฀=฀50฀mL., 33. Mass฀=฀20.036฀–฀0.02฀=฀20.016฀g฀=฀20.02฀g, Reported฀to฀two฀decimal฀places., 20.02, .268 9.27, Density฀=฀ = 9=, 2.16, as฀it฀should฀contain฀three฀significant฀figures., 34. Weight฀of฀metal฀oxide฀฀ =฀3.6฀g, Weight฀of฀metal฀฀, =฀3.2฀g, Weight฀of฀oxygen฀, =฀0.4฀g, Element฀฀, Relative฀No.฀of฀atoms฀, Metal฀฀, ฀ ฀ ฀3.2/64฀=฀1/20฀฀, Oxygen฀ ฀ ฀ ฀ ฀฀0.4/16฀=฀1/40฀฀, ∴฀Formula฀of฀the฀compound฀=฀MnO, , Simple฀ratio, ฀ ฀ 2, ฀ ฀ ฀1, , 36. 4KClO3 , → (3KClO4฀+฀KCl), 4฀moles฀฀, ฀฀฀฀3฀moles, 0.1฀mole฀, ฀฀฀฀0.75฀mole, 37. Ca(OH)2฀+฀CO2฀ , → ฀CaCO3฀+฀H2O, 1฀mole฀, ฀, 1฀mole, 100฀g฀of฀CaCO3฀=฀1฀mole, 0.05฀g฀of฀CaCO3฀=฀0.0005฀mole, ∴฀0.0005฀mole฀of฀CO2฀=฀0.012฀litre, 0.012฀litre฀of฀CO2฀is฀present฀in฀10฀litres฀of฀air, Per฀cent฀of฀CO2฀in฀air฀=฀1.12., 5, 38. C2H2฀+฀ ฀O2฀ , → 2CO2฀+฀H2O, 2, 7, C2H6฀+฀ ฀O2฀ , → ฀2CO2฀+฀3H2O, 2, 3, CH3OH฀+฀ , → ฀O2CO2฀+฀2H2O, 2, C2H5OH฀+฀2CO2฀ , → ฀2CO2฀+฀2H2O, Wt.of nitrogen, ×100 ฀∴฀NH3฀has฀maxi­, M.W.of fertiliser, mum฀per฀cent฀of฀N., , 39. %฀of฀N฀=฀, , 40. One฀mole฀of฀nicotine฀gives฀10฀moles฀of฀CO2, ฀, 0.1฀mole฀of฀nicotine฀gives฀1฀mole฀of฀CO2฀=฀44฀g