JEE Chemistry 2024 Question with Solution

Given: We must identify which species cannot act as an oxidising agent.

Find: The option that cannot undergo reduction further and therefore cannot behave as an oxidising agent.

An oxidising agent accepts electrons and gets reduced. So a species already having its central atom in the lowest possible oxidation state cannot act as an oxidising agent.

For $\mathrm{N}^{3-}$, nitrogen is already in its lowest possible oxidation state, $-3$. Therefore, it cannot be reduced further.

Species such as $\mathrm{BrO}_{3}^{-}$ and $\mathrm{MnO}_{4}^{-}$ are well-known oxidising agents because Br and Mn are in high oxidation states and can gain electrons by reduction.

Therefore, the substance that cannot function as an oxidising agent is $\mathrm{N}^{3-}$. Hence, the correct option is A.

The solution incorrectly labels the option letter as C, but the worked conclusion identifies $\mathrm{N}^{3-}$, which corresponds to option A in the given options.

Given: The options are $\mathrm{N}^{3-}$, $\mathrm{SO}_{4}^{2-}$, $\mathrm{BrO}_{3}^{-}$, and $\mathrm{MnO}_{4}^{-}$.

Find: Which one cannot act as an oxidising agent.

An oxidising agent must be capable of accepting electrons. That means the relevant atom should be able to move to a lower oxidation state.

In $\mathrm{N}^{3-}$, nitrogen has oxidation state $-3$, which is the minimum oxidation state of nitrogen. Since it cannot go below $-3$, it cannot accept electrons further.

Thus $\mathrm{N}^{3-}$ cannot act as an oxidising agent, whereas the other species contain atoms in relatively higher oxidation states and can undergo reduction.

Therefore, the correct option is A.