Which of the following is (are) an endothermic process(es)?
(i) Dilution of sulphuric acid
(ii) Sublimation of dry ice
(iii) Condensation of water vapours
(iv) Evaporation of water

Options

A. Both (i) and (iii)
B. Only (ii)
C. Only (iii)
D. Both (ii) and (iv)

Explanation

To determine which of the given processes are endothermic, we need to understand what an endothermic process is. An endothermic process is one that absorbs heat from the surroundings. Let's analyze each option step by step:

1. **Dilution of Sulphuric Acid (H₂SO₄)**:
- When sulfuric acid is diluted with water, it releases heat. This means that it is an exothermic process, not endothermic.
- **Conclusion**: Not an endothermic process.

2. **Sublimation of Dry Ice (Solid CO₂)**:
- Sublimation is the process where a solid turns directly into a gas without passing through the liquid state. This process requires heat to occur, meaning it absorbs heat from the surroundings.
- **Conclusion**: This is an endothermic process.

3. **Condensation of Water Vapours**:
- In condensation, water vapours (gas) turn into liquid water. This process releases heat to the surroundings, indicating that it is exothermic.
- **Conclusion**: Not an endothermic process.

4. **Evaporation of Water**:
- Evaporation is the process where liquid water turns into water vapour (gas). This process requires heat, which is absorbed from the surroundings.
- **Conclusion**: This is an endothermic process.

### Summary of Findings:
- Endothermic Processes:
- (ii) Sublimation of dry ice
- (iv) Evaporation of water
- Exothermic Processes:
- (i) Dilution of sulphuric acid
- (iii) Condensation of water vapours

### Final Answer:
The endothermic processes among the options provided are:
- (ii) Sublimation of dry ice
- (iv) Evaporation of water

Thus, the correct answer is option number four.

---