Class 11 NEET Chemistry Redox Reactions Questions

Concept: A redox reaction is defined as a chemical process in which both oxidation and reduction occur simultaneously.Explanation:Let us analyze all the given options:1. Evaporation of $\mathrm{H}_{2}\mathrm{O}$: This is merely a physical change (liquid to gas). No change in oxidation states occurs.2. $\mathrm{H}_{2}\mathrm{SO}_{4}$ with $\mathrm{NaOH}$: This is an acid-base neutralization reaction ($\mathrm{H}^+ + \mathrm{OH}^- \rightarrow \mathrm{H}_2\mathrm{O}$). The oxidation states of all elements remain the same.3. In atmosphere $\mathrm{O}_{3}$ from $\mathrm{O}_{2}$ by lightning: The reaction is $3\mathrm{O}_{2} \rightarrow 2\mathrm{O}_{3}$. The oxidation state of oxygen is zero in both $\mathrm{O}_{2}$ and $\mathrm{O}_{3}$, so there is no transfer of electrons.4. Both oxidation and reduction: By definition, a redox (Reduction-Oxidation) reaction is one where both oxidation (loss of electrons) and reduction (gain of electrons) take place simultaneously.Answer: Option B