Water boils at a lower temperature than `100^@C` on a hill station because

Options

A. Water vapours are less at high altitudes
B. Temperature is lower at high altitudes
C. Pressure is lower at high altitudes
D. There is cloud formation at high altitudes

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:**
- The question asks why water boils at a temperature lower than `100°C` on a hill station.

2. **Concept of Boiling Point:**
- The boiling point of water at sea level is `100°C`. This is the temperature at which water changes from liquid to gas (steam) under normal atmospheric pressure.

3. **Effect of Altitude on Atmospheric Pressure:**
- At higher altitudes, such as hill stations, the atmospheric pressure is lower than at sea level. This is due to the thinner air at higher elevations.

4. **Relationship Between Pressure and Boiling Point:**
- The boiling point of a liquid is dependent on the surrounding atmospheric pressure. When the pressure decreases, the boiling point also decreases. This means that water will boil at a temperature lower than `100°C` when the atmospheric pressure is lower.

5. **Conclusion:**
- Therefore, the reason water boils at a lower temperature than `100°C` on a hill station is that the atmospheric pressure is lower at higher altitudes.

6. **Final Answer:**
- Water boils at a lower temperature than `100°C` on a hill station because the atmospheric pressure is lower at higher altitudes.