An alloy of zinc and copper is dissolved in dilute hydrochloric acid. Hydrogen gas is evolved. In this evolution of gas

Options

A. only zinc reacts with dilute hydrochloric acid
B. only copper react with dilute hydrochloric acid
C. both zinc and copper react with dilute hydrochloric acid
D. only copper reacts with water.

Explanation

To solve the question regarding the evolution of hydrogen gas when an alloy of zinc and copper is dissolved in dilute hydrochloric acid, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Components of the Alloy**:
- The alloy consists of two metals: zinc (Zn) and copper (Cu).

2. **Understand the Reaction with Dilute Hydrochloric Acid**:
- When metals react with dilute hydrochloric acid (HCl), they can displace hydrogen gas from the acid.

3. **Refer to the Reactivity Series**:
- Metals have different reactivities, which can be arranged in a reactivity series. In this series, zinc is more reactive than hydrogen, while copper is less reactive than hydrogen.

4. **Determine Which Metal Reacts**:
- Since zinc is more reactive than hydrogen, it will react with hydrochloric acid to produce zinc chloride (ZnCl2) and hydrogen gas (H2).
- The reaction can be represented as:
\[ \text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2 \uparrow \]

5. **Consider the Role of Copper**:
- Copper, being less reactive than hydrogen, will not participate in the reaction. Therefore, it will not contribute to the evolution of hydrogen gas.

6. **Conclusion**:
- The evolution of hydrogen gas during the reaction is solely due to the presence of zinc in the alloy. Copper does not affect the reaction since it does not react with dilute hydrochloric acid.

### Final Answer:
In the evolution of hydrogen gas when an alloy of zinc and copper is dissolved in dilute hydrochloric acid, only zinc reacts with the acid to produce hydrogen gas.

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