5. Slaking of lime is (i) An endothermic reaction (ii) An exothermic reaction (iii) A combination reaction (iv) A decomposition reaction. A) (i) & (iii) B) (i) & (iv) C) (ii) & (iii) D) (ii) & (iv) 6. The oxidation number of sulphur in sulphuric acid is A) 2 B) 4 C) 3 D) 6 7. A copper vessel acquires a green coloured coating when kept in moist air for a few days. The green coloured subs†an ce is chemically A) Acidic copper oxide B) Basic copper sulphate C) Hydrated copper sulphate D) Basic copper carbonate.

Q. Slaking of lime is
(i) an endothermic reaction
(ii) an exothermic reaction
(iii) a combination reaction
(iv) a decomposition reaction

Q. A copper vessel acquires a green coloured coating when kept in moist air for a few days. The green coloured substance is chemically

Q.

When copper vessels are exposed to moist air for a long time, a green coating is formed. Which are the constituents of the coating?
(i) Copper hydroxide
(ii) Copper carbonate
(iii) Copper oxide

Q.

Select the correct answers :

(a) Colour of an aqueous solution of copper sulphate is

(i) Green (ii) Brown (iii) Blue (iv) Yellow

(b) Colour of the precipitate formed on adding $NaOH$ solution to iron (II) sulphate solution is

(i) White (ii) Brown (iii) Green (iv) Pale blue

(c) A metal which produces hydrogen on reacting with alkali as well as with acid.

(i) Iron (ii) Magnesium (iii) Zinc (iv) Copper

Q. You are given the following materials:
(i) Iron nails
(ii) Copper sulphate solution
(iii) Barium chloride solution
(iv) Copper powder
(v) Ferrous sulphate crystals
(vi) Quicklime

Identify the type of chemical reaction taking place when:
(a) Barium chloride solution is mixed with copper sulphate solution and a white precipitate is observed.
(b) On heating copper powder in air in a china dish, the surface of copper powder turns black.
(c) On heating green coloured ferrous sulphate crystals, reddish brown solid is left and smell of a gas having odour of burning sulphur is experienced.
(d) Iron nails when left dipped in blue colour copper sulphate solution become brownish in colour and the blue colour of copper sulphate fades away.
(e) Quick lime reacts vigorously with water releasing a large amount of heat.
Write chemical equations for each one of the above reactions.