Answer the question on the basis of passage given below:

Nitrogen forms a large number of oxoacids such as $H_2N_2O_2$, (hyponitrous acid), $HNO_2$, (nitrous acid) and $HNO_3$, (nitric acid). Amongst these, $HNO_3$, is the most important. It is used in the manufacture of ammonium nitrate for fertilisers and other nitrates for use in explosives. It is also used to prepare many important organo-nitro compounds like nitroglycerine, trinitrotoluene etc. It acts as a strong oxidizing agent and used as an oxidiser in rocket fuels.

Which of the following behaves as the strongest oxidising agent?

$HNO_3$

The correct answer is Option (2) → $HNO_3$.

To determine which compound behaves as the strongest oxidizing agent among the given options, we need to understand the oxidation states and the typical behavior of each substance in redox reactions.

Analysis of Each Compound:

1. HNO₂ (Nitrous Acid):

In HNO₂, nitrogen is in the +3 oxidation state. HNO₂ can act as both an oxidizing agent and a reducing agent, depending on the reaction conditions. It is a moderate oxidizer but not as strong as HNO₃. It can oxidize some metals but is limited in its overall oxidizing ability.

2. HNO₃ (Nitric Acid):

In HNO₃, nitrogen is in the +5 oxidation state. HNO₃ is a very strong oxidizing agent, especially in concentrated form. It can oxidize a wide range of substances, including metals (like zinc or copper), organic compounds, and nonmetals (like sulfur). The presence of nitrogen in a higher oxidation state (+5) allows it to readily accept electrons.

3. NH₃ (Ammonia):

In NH₃, nitrogen is in the -3 oxidation state.Ammonia primarily acts as a reducing agent rather than an oxidizer. It donates electrons to other substances, thereby reducing them. It is not known for oxidizing other substances effectively.

4. H₂N₂O₂ :

In H₂N₂O₂ , nitrogen can vary between -2 to -1 depending on the structure.

H₂N₂O₂  can act as both an oxidizing and reducing agent. It has some oxidizing potential but is generally less effective than HNO₃ for oxidation reactions.

Conclusion:
When comparing these substances:

HNO₃ has a high oxidation state of nitrogen and is known for its strong oxidizing properties, capable of oxidizing metals and other substances effectively. HNO₂ is a moderate oxidizer. NH₃ is a reducing agent. H₂N₂O₂ can act as an oxidizer, but not as strongly as HNO₃.

Thus, HNO₃ (Nitric Acid) is the strongest oxidizing agent among the options provided. Its ability to donate oxygen and accept electrons makes it highly effective in oxidation reactions.