Question

When zinc metal reacts with sodium hydroxide solution on heating, the gas evolved:

• A. Turns lime water milky
• B. Supports combustion
• C. Burns with a pop sound
• D. Has a pungent odor.

Answer 1

The correct option is C

Burns with a pop sound

The explanation for the correct option

(C) burns with a pop sound

The reaction of zinc with sodium hydroxide

Zinc$\left(\mathrm{Zn}\right)$ reacts with sodium hydroxide$\left(\mathrm{NaOH}\right)$ to form sodium zincate$\left({\mathrm{Na}}_2{\mathrm{ZnO}}_2\right)$ and hydrogen gas$\left({\mathrm{H}}_2\right)$.

$2\mathrm{NaOH}\left(\mathrm{aq}\right)+\mathrm{Zn}\left(\mathrm{s}\right)\to {\mathrm{Na}}_2{\mathrm{ZnO}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

Hydrogen gas burns with a pop sound.

Explanation of the incorrect options

(A) turns lime water milky

Hydrogen gas does not turn lime water milky.

(B) supports combustion

Hydrogen gas does not support combustion.

(D) has a pungent odor

Hydrogen gas is odorless.

As when zinc reacts with sodium hydroxide, hydrogen gas is made which burns with a pop sound.

Hence, the correct option is (C).