Question

Pure nitric acid is colourless but the acid obtained in the laboratory is slightly yellow. The yellow colour is due to_____________.

• A. The dissolution of NO in the acid.
• B. The dissolution of $N_{2}O$ in the acid.
• C. The dissolution of $N{O}_2$ in the acid.
• D. The dissolution of $N_2{O}_5$ in the acid.

Answer 1

The correct option is C The dissolution of $N{O}_2$ in the acid.

Pure nitric acid is colourless but the acid obtained in the laboratory is slightly yellow. The yellow colour is due to dissolution of reddish brown coloured nitrogen dioxide gas in the acid. This gas is produced due to the thermal decomposition of nitric acid.

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