JEE Main 2022 · 28 July · evening · Single correct · +4 / −1
Concentrated HNO₃ reacts with Iodine to give :
- (a) HI, NO₂ and H₂ O
- (b) HIO₂, N₂ O and H₂ O
- (c) HIO₃, NO₂ and H₂ O
- (d) HIO₄, NO₂ and H₂ O
Answer and solution
Answer (c) HIO₃, NO₂ and H₂ O
Solution
Chemistry ma’am · 3 steps
Concentrated nitric acid oxidises iodine to +5 as HIO₃ and is itself reduced to NO₂.
- Who is oxidised. HNO₃ is a strong oxidising agent, so iodine must lose electrons. Its oxidation state rises from 0 in I₂ to +5 in iodic acid, HIO₃, the most stable oxoacid of iodine.
- Who is reduced. Concentrated HNO₃ is reduced to NO₂, with nitrogen going from +5 to +4. Each I₂ gives up 2 × 5 = 10 electrons, so 10 HNO₃ are needed to accept them.
I₂ + 10HNO₃ → 2HIO₃ + 10NO₂ + 4H₂O
- So. The products are HIO₃, NO₂ and H₂O, which is option (c).
The idea to keep. Concentrated HNO₃ gives NO₂ and pushes non-metals to a stable high oxidation state: I to HIO₃, S to H₂SO₄, P to H₃PO₄, C to CO₂.
Answer from the NTA final answer key. Solution by PrepWiser.