Question

What do you observe when

(a) Iron nail is kept in copper sulphate solution for sometime.

(b) Phenolphthalein is added to sodium hydroxide solution.

(c) Blue litmus paper is dipped in dilute hydrochloric acid.

(d) Lead nitrate is heated.

(e) Magnesium ribbon is burnt in oxygen.

(f) Ammonia is brought in contact of hydrogen chloride.gas.

Answer 1

(a) A brown layer of copper gets deposited on iron nail. This is due to a chemical reaction.

Fe (s) + CuSO₄ (aq) → FeSO₄ (aq) + Cu (s)

(b) The solution turns pink.

(c) Blue litmus turns red in an acid solution.

(d) The pale yellow solid is lead monoxide, the reddish brown gas is nitrogen dioxide and the colorless gas is oxygen.

(e) Magnesium ribbon bums with a dazzling white light and produces a white powder which is magnesium oxide.

The reaction can be represented as

2Mg + O ₂ → 2MgO (white powder)

(f) Ammonia and hydrogen chloride, both compounds, combine to form a compound, ammonium chloride.