JEE Main 2021 · 16 March · morning · Single correct · +4 / −1
Given below are two statements :
Statement I : H₂O₂ can act as both oxidising and reducing agent in basic medium.
Statement II : In the hydrogen economy, the energy is transmitted in the form of dihydrogen.
In the light of the above statements, choose the correct answer from the options given below :
- (a) Both statement I and statement II are false
- (b) Statement I is false but statement II is true
- (c) Statement I is true but statement II is false
- (d) Both statement I and statement II are true
Answer and solution
Answer (d) Both statement I and statement II are true
Solution
Chemistry ma’am · 4 steps
Oxygen in H₂O₂ is at -1, so it can go either way; the hydrogen economy ships H₂ itself.
- Oxidation state of O. In H₂O₂ each oxygen is at -1. That lies between -2 (in H₂O or OH⁻) and 0 (in O₂). So oxygen can be reduced to -2 or oxidised to 0, and the molecule can play either role.
Role in basic medium Example reaction Change in O Oxidising agent 2Fe²⁺ + H₂O₂ → 2Fe³⁺ + 2OH⁻ -1 → -2 Reducing agent I₂ + H₂O₂ + 2OH⁻ → 2I⁻ + 2H₂O + O₂ -1 → 0 - Statement I. Both kinds of reaction are known in basic medium, so Statement I is true.
- Statement II. In the hydrogen economy, energy is stored and carried as dihydrogen, not as electric power. The H₂ is moved by pipeline or in tanks and then burnt or used in fuel cells where the energy is needed. So Statement II is true.
- So. Both statements are true, which is option (d).
The idea to keep. An element in an intermediate oxidation state can usually both oxidise and reduce, in acid or in base. The hydrogen economy moves energy as H₂, not as electricity.
Answer from the NTA final answer key. Solution by PrepWiser.