When dilute hydrochloric acid is added to zinc pieces taken in a test tube

Options

A. no change takes place
B. the colour of the solution becomes yellow
C. a pungent smelling gas gets liberated
D. small bubbles of hydrogen gas appear on the surface of zinc pieces.

Explanation

### Step-by-Step Solution:

1. **Identify the Reactants**: The reactants in this reaction are dilute hydrochloric acid (HCl) and zinc (Zn) pieces.

2. **Write the Chemical Equation**: When dilute hydrochloric acid reacts with zinc, the chemical reaction can be represented as:
\[ \text{Zn (s)} + 2 \text{HCl (aq)} \rightarrow \text{ZnCl}_2 \text{ (aq)} + \text{H}_2 \text{ (g)} \]

3. **Identify the Products**: The products of this reaction are zinc chloride (ZnCl₂) in aqueous form and hydrogen gas (H₂).

4. **Observe the Reaction**: When dilute hydrochloric acid is added to zinc pieces, you will observe the following:
- Bubbles of hydrogen gas start to form on the surface of the zinc pieces.
- The solution may become slightly cloudy due to the formation of zinc chloride.

5. **Conclusion**: The reaction produces hydrogen gas, which is visible as bubbles, indicating that a chemical reaction has taken place.