Some materials like magnesium ribbon, aluminium foil, copperr wire and charcoal (powder) were taken in different test tubes labelled as P, Q, R and S. 5 mL of dilute hydrochloric acid was added to each test tube. When a burning matchstick is brought near the mouth of each test tube, in which cases pop sound would be heard ?

Options

A. Only P
B. Only P and Q
C. Only Q and S
D. Only P, Q and R

Explanation

To determine in which test tubes a pop sound would be heard when a burning matchstick is brought near the mouth of each test tube containing different materials and dilute hydrochloric acid, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Materials and Their Properties**:
- Test Tube P: Magnesium ribbon
- Test Tube Q: Aluminium foil
- Test Tube R: Copper wire
- Test Tube S: Charcoal powder

2. **Understand the Reaction with Dilute Hydrochloric Acid**:
- When metals react with dilute hydrochloric acid (HCl), they produce a metal salt and hydrogen gas (H2).
- The pop sound is produced when hydrogen gas burns, indicating its presence.

3. **Evaluate Each Material**:
- **Test Tube P (Magnesium)**:
- Magnesium is a reactive metal. It reacts with HCl to form magnesium chloride (MgCl2) and hydrogen gas (H2).
- Reaction: Mg + 2HCl → MgCl2 + H2 ↑
- **Conclusion**: Pop sound will be heard.

- **Test Tube Q (Aluminium)**:
- Aluminium is also a reactive metal. It reacts with HCl to form aluminium chloride (AlCl3) and hydrogen gas (H2).
- Reaction: 2Al + 6HCl → 2AlCl3 + 3H2 ↑
- **Conclusion**: Pop sound will be heard.

- **Test Tube R (Copper)**:
- Copper is less reactive and does not react with dilute hydrochloric acid.
- **Conclusion**: No reaction, so no pop sound will be heard.

- **Test Tube S (Charcoal)**:
- Charcoal is a form of carbon, which is a non-metal. Non-metals do not react with dilute acids to produce hydrogen gas.
- **Conclusion**: No reaction, so no pop sound will be heard.

4. **Final Conclusion**:
- The pop sound will be heard in Test Tubes P (Magnesium) and Q (Aluminium) only.

### Summary:
- **Pop sound heard in**: Test Tube P (Magnesium) and Test Tube Q (Aluminium).
- **No pop sound heard in**: Test Tube R (Copper) and Test Tube S (Charcoal).