Question

Which of the following is an acidic oxide?

• A. CO
• B. NO
• C. $N_2O$
• D. $N_2O_5$

Hint:

The higher the oxidation state of the central non-metal atom, the more highly acidic the corresponding oxide will be. ($N_2O$ and $NO$ are neutral, but $N_2O_3$, $NO_2$, and $N_2O_5$ are progressively more acidic).

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
We must identify which of the provided gaseous oxides demonstrates acidic chemical characteristics, meaning it will react with water to form an acid or react directly with a base to form a salt.

Step 2: Detailed Explanation:
Oxides of non-metals are generally classified as either acidic or neutral.
There are three very common, widely recognized neutral oxides of non-metals that you must memorize: Carbon monoxide ($CO$), Nitric oxide ($NO$), and Nitrous oxide ($N_2O$). These do not exhibit acidic or basic properties in aqueous solutions.
Therefore, options (a), (b), and (c) are all strictly neutral oxides.
Nitrogen pentoxide ($N_2O_5$) is an oxide of nitrogen where nitrogen is in its highest +5 oxidation state.
Generally, the acidic character of non-metal oxides increases dramatically as the oxidation state of the central atom increases. $N_2O_5$ is strongly acidic. When dissolved in water, it readily forms strong nitric acid:
$N_2O_5 + H_2O \rightarrow 2HNO_3$.

Step 3: Final Answer:
$N_2O_5$ is the only acidic oxide on the list, matching option (d).