JEE Main 2020 · 6 September · evening · Single correct · +4 / −1
The reaction of NO with N₂O₄ at 250 K gives :
- (a) N₂O₃
- (b) N₂O₅
- (c) N₂O
- (d) NO₂
Answer and solution
Answer (a) N₂O₃
Solution
Chemistry ma’am · 3 steps
Nitrogen at +2 meets nitrogen at +4, so the product sits in between at +3: that is N₂O₃.
- Oxidation states. In NO, nitrogen is +2. In N₂O₄, each nitrogen is +4. When two compounds of the same element combine, the product usually has an oxidation state between the two.
2NO + N₂O₄ →(250 K) 2N₂O₃
Option Oxidation state of N Between +2 and +4? (a) N₂O₃ +3 yes (b) N₂O₅ +5 no, above both (c) N₂O +1 no, below both (d) NO₂ +4 no, same as the reactant - Why 250 K. N₂O₃ is stable only at low temperature. When it is warmed, it splits back into NO and NO₂, so the reaction is carried out cold.
- So. The left side has 4 N and 6 O, exactly enough for two N₂O₃, and nitrogen ends up at +3. The answer is (a) N₂O₃.
The idea to keep. When two oxides of the same element combine, the product has the in-between oxidation state. Reaching a higher or lower state needs a separate oxidant or reductant.
Answer from the NTA final answer key. Solution by PrepWiser.