Assertion `(A)`: A small piece of zinc dissolves in dilute nitric acid but no hydrogen is evolved.
Reason `(R)` : `HNO_3` is an oxidising acid and oxidises hydrogen evolved to water.

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 (A) is incorrect, but (R) is correct.

Explanation

To solve the assertion and reason question, we will analyze both statements step by step.

### Step 1: Analyze the Assertion
The assertion states: "A small piece of zinc dissolves in dilute nitric acid but no hydrogen is evolved."

- When zinc (Zn) reacts with dilute nitric acid (HNO3), it typically forms zinc nitrate (Zn(NO3)2) and may produce nitrogen oxides (NO or N2O) instead of hydrogen gas. This is because nitric acid acts as an oxidizing agent.

### Step 2: Analyze the Reason
The reason states: "HNO3 is an oxidizing acid and oxidizes hydrogen evolved to water."

- Nitric acid (HNO3) is indeed an oxidizing agent. In reactions involving zinc and nitric acid, if hydrogen gas were to be produced, it would be oxidized by the nitric acid to form water (H2O). Thus, the statement about HNO3 oxidizing hydrogen to water is correct.

### Step 3: Conclusion
- Both the assertion and the reason are correct. The assertion correctly states that no hydrogen gas is evolved when zinc reacts with dilute nitric acid, and the reason correctly explains that if hydrogen were produced, it would be oxidized to water by the nitric acid.

### Final Answer
Both the assertion (A) and the reason (R) are correct, and the reason (R) is the correct explanation for the assertion (A).

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