Iqbal treated a lustrous, divalent element M with sodium hydroxide.
Question:

Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in reaction mixture. He made the same

observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both

the reactions.

Solution:

The divalent element M is a metal. It reacts with both sodium hydroxide (alkali) and dilute hydrochloric acid to evolve hydrogen gas

$\mathrm{M}(s)+2 \mathrm{NaOH}(a q) \longrightarrow \mathrm{Na}_{2} \mathrm{MO}_{2}(a q)+\mathrm{H}_{2}(g)$

$\mathrm{M}(s)+2 \mathrm{HCl}(a q) \longrightarrow \mathrm{MCl}_{2}(a q)+\mathrm{H}_{2}(g)$

The gas burns with a pop sound when a burning match stick is brought near it.