What do you observe when dil. HCl is added on Zn pieces taken in a test tube? How would you identify the gas evolved? Write on use of this gas.

Explanation

### Step-by-Step Text Solution

1. **Observation of Reaction**:
When dilute hydrochloric acid (HCl) is added to zinc (Zn) pieces in a test tube, a chemical reaction occurs. You will observe the formation of bubbles, which indicates the evolution of a gas. The reaction can be represented by the following equation:
\[ \text{Zn (s)} + 2\text{HCl (aq)} \rightarrow \text{ZnCl}_2 (aq) + \text{H}_2 (g) \]
Here, zinc chloride (ZnCl₂) is formed, and hydrogen gas (H₂) is evolved.
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