Assertion (A): `O_(3)` can act as an oxidising agent as wll as a reducing agent, but `SO_(2)` can act only as an oxidant.
Reason (R ): The oxidation number of `O` in `O_(3)` is zero, and the oxidiation number of `S` in `SO_(2)` is `+4`.

Options

A. If both `(A)` and `(R )` are correct and `(R )` is the correct explanation of `(A)`.
B. If both `(A)` and `(R )` are correct but `(R )` is not the correct explanation of `(A)`.
C. If `(A)` is correct but `(R )` is incorrect.
D. If both `(A)` and `(R )` are incorrect.

Answer

D

Explanation

Correct (A): `SO_(2)` can act both as an oxidising and a reducing agent. `O_(3)` can act only as an oxidant.
Reason: The oxidation number of `O` in `O_(3)` is zero. It can only decrease from zero to `-1` or `-2` but cannot increase to `+2`. Therefore, it can act as an oxidant only. In `SO_(2)`, the oxidation number of `S` is `+4`. It can have a minimum oxidation number of `-2` and maximum of `+6`. Its oxidation number either decreases or increases, and hence, it can act both as an oxidising and a reducing agent.