Choose the substances given in the box below to answer the following questions:

Iron	Magnesium sulphite	Zinc	Sodium sulphide
Lead	Ferric chloride	Copper	Ferrous sulphate

(a) The metal that will not produce hydrogen gas when reacted with dilute acids.

(b) The compound that will produce sulphur dioxide gas when reacted with dilute HCl.

(c) The solution of this compound produces dirty green precipitate with NaOH.

(a) Copper

(b) Magnesium Sulphite

(c) Ferrous Sulphate

Explanation

(a) Copper (Cu) is less reactive and lies below hydrogen in the reactivity series, so it cannot displace hydrogen from dilute acids and therefore does not produce hydrogen gas.

(b) Magnesium sulphite reacts with dilute hydrochloric acid to give magnesium chloride, sulphur dioxide gas, and water. Brisk effervescence due to SO₂ (pungent, choking smell).

$\text{MgSO}$3(s) + 2\text{HCl}(aq) \rightarrow \text{MgCl}2(aq) + \text{SO}2(g)\uparrow + \text{ H}2\text{O}(l)

(c) Ferrous sulphate solution contains Fe²⁺ ions. On adding NaOH, these ions react with hydroxide ions to form ferrous hydroxide, which is a dirty green precipitate.

$\text{FeSO}$4(aq) + 2\text{NaOH}(aq) \rightarrow \text{Fe(OH)}2(s)\downarrow + \text{Na}2\text{SO}4(aq)