Question

A gaseous substance dissolves in water giving a pale blue solution which decolourises $KMn{O}_4$ and oxidises $KI$ to $I_2$. The gaseous substance is :

• A. $N_2{O}_5$
• B. $N{H}_3$
• C. $N_2{O}_3$
• D. $HN{O}_3$

Answer 1

The correct option is C $N_2{O}_3$

$N_2{O}_3$, which has a deep blue colour $N_2{O}_3+H_{2}O\to HN{O}_3+HN{O}_2$

$2HN{O}_2\to N_2{O}_3+H_{2}O$

Here, $HN{O}_2$ decolorises $KMn{O}_4$ and $HN{O}_3$ oxidises $KI$ to $I_2$.