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Give an example each for the mixture having the following characteristics. Suggest a suitable method to separate the components of these mixtures (a) A volatile and a non-volatile component. (b) Two volatile components with appreciable difference in boiling points. (c) Two immiscible liquids. (d) One of the components changes directly from solid to gaseous state. (e) Two or more coloured constituents soluble in some solvent.

Answer: (a) Mixture of acetone and water. It can be separated by distillation. (b) Mixture of petrol and kerosene. Can be separated by... View Article

Name the process associated with the following (a) Dry ice is kept at room temperature and at one atmospheric pressure. (b) A drop of ink placed on the surface of water contained in a glass spreads throughout the water. (c) A potassium permanganate crystal is in a beaker and water is poured into the beaker with stirring. (d) An acetone bottle is left open and the bottle becomes empty. (e) Milk is churned to separate cream from it. (f) Settling of sand when a mixture of sand and water is left undisturbed for some time. (g) Fine beam of light entering through a small hole in a dark room, illuminates the particles in its paths

Answer: (a) Dry ice is kept at room temperature and at one atmospheric pressure - Sublimation (b) A drop of ink placed on the surface of water... View Article

Classify the following as physical or chemical properties (a) The composition of a sample of steel is 98% iron, 1.5% carbon and 0.5% other elements. (b) Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas. (c) Metallic sodium is soft enough to be cut with a knife. (d) Most metal oxides form alkalis on interacting with water.

Answer: Most of the substances that we see around have certain characteristics and properties by which they can be classified or identified. As... View Article

Two chemical species X and Y combine together to form a product P which contains both X and Y X + Y → P. X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following concerning the species X, Y and P are correct? (i) P is a compound (ii) X and Y are compounds (iii) X and Y are elements (iv) P has a fixed composition (a) (i), (ii) and (iii), (b) (i), (ii) and (iv) (c) (ii), (iii) and (iv) (d) (i), (iii) and (iv)

Answer: (d) (i), (iii) and (iv) X + Y → P X and Y cannot be further broken down into simpler substances. Hence X and Y are elements. P can... View Article

Two substances, A and B were made to react to form a third substance, A2B according to the following reaction 2A + B → A2B which of the following statements concerning this reaction are incorrect? (i) The product A2B shows the properties of substances A and B (ii) The product will always have a fixed composition (iii) The product so formed cannot be classified as a compound (iv) The product so formed is an element (a) (i), (ii) and (iii), (b) (ii), (iii) and (iv) (c) (i), (iii) and (iv) (d) (ii), (iii) and (iv)

Answer: (c) (i), (iii) and (iv) 2A + B → A2B A2B is a compound made up of two elements A and B in a fixed ratio. The properties of a... View Article