JEE Main 2021 · 17 March · evening · Single correct · +4 / −1
The set that represents the pair of neutral oxides of nitrogen is :
- (a) NO and N₂O
- (b) N₂O and NO₂
- (c) NO and NO₂
- (d) N₂O and N₂O₃
Answer and solution
Answer (a) NO and N₂O
Solution
Chemistry ma’am · 3 steps
Low oxidation state of nitrogen means a neutral oxide, so look for +1 and +2.
- What neutral means. A neutral oxide gives no acid or base with water and reacts with neither acids nor bases. Among non-metal oxides, this happens when the non-metal is in a low oxidation state.
- Find oxidation states. Each O counts as -2, so work out N in each oxide. Higher oxidation states of N make the oxide acidic, because it then dissolves in water to give an oxoacid.
Oxide Oxidation state of N With water Nature N₂O +1 no acid formed neutral NO +2 no acid formed neutral N₂O₃ +3 N₂O₃ + H₂O → 2HNO₂ acidic NO₂ +4 2NO₂ + H₂O → HNO₂ + HNO₃ acidic - So. The only neutral oxides here are N₂O and NO. Option (a) is the pair.
The idea to keep. Learn the three common neutral oxides together: N₂O, NO and CO. Every other nitrogen oxide, from N₂O₃ up to N₂O₅, is acidic.
Answer from the NTA final answer key. Solution by PrepWiser.