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A+ CHEMISTRY-STD VIII, , STD-8-FIRST BELL-CLASS-5, Chapter-2, BASIC CONSTITUENTS OF MATTER, The earth in which we live is rich with diverse substances. Most of these substances are present in, different physical state such as mixtures and a few others are pure substances., , Classify the substance according to pure substance & mixtures,  Potassium permanganate solution, salt solution, sugar solution, water, copper sulphate solution, Iron,, sulphur, carbon, copper., , , , MIXTURES, PURE SUBSTANCE, Potassium permanganate solution, Sulphur, Salt solution, Carbon, Copper sulphate solution, Copper, Sugar solution, Iron, Pure substance and mixtures are made of extremely small particles., , Activity 1, Take one or two piece of camphor in a china dish & heat the china dish slowly., Observation : Camphor disappears completely, but smell spreads in the air., Conclusion : Camphor has spread in air as extremely small particle., Activity 2, Water taken in a watch glass is getting evaporate., Observation : Water vapour cannot be seen when it evaporates., Conclusion : Evaporation of the water cannot be seen because during the evaporation water changed, into very minute particle., A+ BLOG- www.apluseducare.blogspot.com Whatsapp 9072708051, , Page 1

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A+ CHEMISTRY-STD VIII, , , It may therefore be learnt that all the substances like water, camphor, sugar candy etc are, made up of minute particles., , Activity 3, , Can pure substances be further decomposed?, Fill one quarter of a boiling tube with sugar and closed it with a piece of cotton, then heat the boiling, tube strongly., Observation :, A black precipitate is formed and water vapour is seen on the side of the boiling tube, Conclusion :, Carbon & Water are the components of heating sugar carbon obtained by, heating sugar cannot be further divided but water can., Sir. Humphry Davy (1778 - 1829), , , , He proved that when electricity passed through water it split into hydrogen and oxygen, , Henry Cavendish (1731 – 1810), , , , He discovered that hydrogen burn in oxygen to form water., , , , Sugar is a pure substance which can be further divided into carbon, hydrogen, oxygen. Another pure, substance water can be divided into hydrogen and oxygen. But pure substances like carbon,, hydrogen, oxygen, gold and silver cannot be further divided into its components by chemical, reaction., , A+ BLOG- www.apluseducare.blogspot.com Whatsapp 9072708051, , Page 2

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A+ CHEMISTRY-STD VIII, , , Not all pure substances can be further divided., , ELEMENTS AND COMPOUNDS,  There are of two kinds of pure substances,  Elements are pure substance which cannot be split into simpler components through chemical, processes., Example, 1. Hydrogen, 2. Oxygen, 3. Chlorine,  Compounds are substances formed by the combination of two or more elements through chemical, reactions., Example, 1. Water, 2. Mercuric oxide, 3. Potassium permanganate, Follow up activity, Classify the following into elements & compounds, Ammonia, Sugar, Nitrogen, Sodium chloride, Copper sulphate, Sodium, Carbon, , Prepared by:, , Neethu E V, HST PS, Iringannur Hss Calicut, More Resources, Visit https://apluseducare.blogspot.com/, , A+ BLOG- www.apluseducare.blogspot.com Whatsapp 9072708051, , Page 3