Question

Which of the following is the reddish-brown gas released during the decomposition of nitric acid?

• A. Hydrogen
• B. Nitric oxide
• C. Nitrous oxide
• D. Nitrogen dioxide

Answer 1

The correct option is D

Nitrogen dioxide

Nitric acid dissociates to produce a reddish-brown nitrogen dioxide $\left(N{O}_2\right)$ gas. The equation for the reaction for the dec of nitric acid is given below.

$4HN{O}_3\to 2H_{2}O+4N{O}_2+O_2$

Note: Pure nitric acid is a colourless liquid. But the nitric acid obtained in the laboratory is pale yellow in colour because of $N{O}_2$ gas dissolves in the nitric acid giving it the pale yellow colour.