Question

Hydrochloric acid reacts with galena to liberate which gas :

• A. Chlorine
• B. Sulphur dioxide
• C. Hydrogen sulphide
• D. Nitrogen

Answer 1

The correct option is C

Hydrogen sulphide

Explanation for correct option:

(C) Hydrogen sulphide:

Hydrochloric acid reacts with galena to liberate hydrogen sulphide gas.

• The reaction of metallic sulphides and bisulphides with hydrochloric acid forms a colourless gas.
• This gas is hydrogen sulphide and it has a pungent odour.
• Galena is an ore of lead sulphide and the chemical formula is $\mathrm{PbS}$.
• So, when galena is treated with dilute hydrochloric acid, it forms hydrogen sulphide, and sodium chloride.
• Therefore, option (C) hydrogen sulphide is correct.

$$\begin{gathered} PbS+2HCl\to PbC{l}_2+H_{2}S \\ GalenaHydrochloricacid\to LeadchlorideHydrogensulphide \end{gathered}$$