X reacts with dilute nitric acid to form 'laughing gas' . What is X ?

Options

A. `Cu`
B. `P_4`
C. `S_8`
D. `Zn`

Answer

To solve the question "X reacts with dilute nitric acid to form 'laughing gas'. What is X?", we can follow these steps:

### Step-by-Step Solution:

1. **Identify 'Laughing Gas':**
- The term 'laughing gas' refers to nitrous oxide, which has the chemical formula \( N_2O \).

2. **Understand the Reaction:**
- We need to find a substance \( X \) that reacts with dilute nitric acid (\( HNO_3 \)) to produce \( N_2O \).

3. **Consider Possible Reactants:**
- Common metals that react with dilute nitric acid include zinc (Zn), magnesium (Mg), and iron (Fe).

4. **Write the Reaction for Zinc:**
- When zinc reacts with dilute nitric acid, the reaction can be represented as:
\[ Zn + 4 HNO_3 \rightarrow Zn(NO_3)_2 + 2 H_2O + N_2O \]
- This shows that zinc produces nitrous oxide when it reacts with dilute nitric acid.

5. **Verify the Reaction:**
- The balanced equation confirms that zinc is indeed a reactant that produces \( N_2O \) along with zinc nitrate and water.

6. **Conclusion:**
- Therefore, the substance \( X \) that reacts with dilute nitric acid to form laughing gas is zinc (Zn).

### Final Answer:
- \( X = \text{Zinc (Zn)} \)