Question

When dilute hydrochloric acid is added to granulated zinc placed in a test tube, the observation made is that

• A. the surface of the metal turns shining.
• B. the reaction mixture turns milky.
• C. odor of chlorine is observed.
• D. a colorless and odorless gas is evolved with bubbles.

Answer 1

The correct option is D

a colorless and odorless gas is evolved with bubbles.

The explanation for the correct option (D):

• In the reaction between metal and acid, the Hydrogen ion (${\mathrm{H}}^{+}$) in the acid is displaced by metal and hence it leads to the formation of salt along with Hydrogen gas (${\mathrm{H}}_2$).
• When granulated Zinc ($\mathrm{Zn}$) is added to a dilute solution of Hydrochloric acid ($\mathrm{HCl}$), it leads to the formation of Zinc chloride (${\mathrm{ZnCl}}_2$) salt with the evolution of Hydrogen gas. The gas evolved is colorless and odourless.

$\mathrm{Zn}\left(\mathrm{s}\right)+\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{ZnCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

Final Answer: Hence, option (D) is correct. When dilute hydrochloric acid is added to granulated zinc placed in a test tube, colorless and odorless gas is evolved with bubbles.