Question

Which of the following can not act as an oxidising agent?

• A. MnO₄^-
• B. SO₂^-
• C. N₃^-
• D. BrO₃^-

Answer 1

The Correct Option is C

To determine which compound cannot act as an oxidising agent, we must understand what an oxidising agent is. An oxidising agent, or oxidant, is a substance that has the ability to oxidize other substances—meaning, it accepts electrons from them. Thus, a good oxidising agent has a tendency to gain electrons and, in the process, is reduced.

Let's analyze each option: 

• MnO₄^- (Permanganate Ion): The permanganate ion is a powerful oxidising agent, especially in acidic media. It can be reduced from Mn⁷⁺ to Mn²⁺ (or even MnO₂), which involves a significant gain of electrons. Therefore, MnO₄^- definitely acts as an oxidising agent.
• SO₂^- (Sulfur Dioxide Ion): This is a bit unclear as SO₂ is typically a gas and not commonly known as an ion in this form. However, SO₂ can be both a reducing agent and an oxidising agent under different conditions, but its ionized form, SO₂^2-, acts more as a reducing agent. But for the analysis given in the question, we must consider SO₂ in an oxidising capability context.
• N₃^- (Azide Ion): The azide ion is typically not an oxidising agent. It is more often involved in nucleophilic reaction processes or acts in explosive compounds due to its instability. Thus, it does not generally function as an oxidising agent.
• BrO₃^- (Bromate Ion): Like MnO₄^-, BrO₃^- is a known strong oxidising agent. It can be reduced from Br⁵⁺ to Br^-, accepting electrons in the process.

From this analysis, it's evident that the azide ion (N₃^-) does not typically act as an oxidising agent.

Conclusion: The substance that cannot act as an oxidising agent is N₃^-.

Answer 2

In \( \text{N}^{3-} \), nitrogen is present in its lowest possible oxidation state. Hence, it cannot be further reduced and cannot act as an oxidizing agent.
The correct option is (C) : N₃^-