Steam is passed through the water contained in a beaker. The water can boil, when the steam is at

Options

A. atmospheric pressure
B. pressure height than the atmosphere
C. pressure lower than the atmosphere
D. any pressure

Answer

To solve the question, "Steam is passed through the water contained in a beaker. The water can boil when the steam is at", we need to analyze the relationship between steam, pressure, and boiling point.

### Step-by-step Solution:

1. **Understanding Steam**:
- Steam is water vapor that has been heated to a point where it becomes a gas. It carries a significant amount of heat energy.

2. **Properties of Steam**:
- Steam exists at a high temperature and typically at a low pressure when it is generated. This means that when steam is introduced to water, it can transfer heat effectively.

3. **Boiling Point of Water**:
- The boiling point of water is influenced by pressure. At standard atmospheric pressure (1 atm), water boils at 100°C. However, if the pressure is reduced, the boiling point of water decreases.

4. **Effect of Low Pressure**:
- When steam is passed through water, if the steam is at a low pressure, it creates a condition where the pressure above the water is lower than atmospheric pressure. This allows the water to boil at a lower temperature.

5. **Achieving Equilibrium**:
- As steam is introduced, the water will try to reach a state of equilibrium. When the pressure is lower, water molecules can escape into the vapor phase more easily, leading to boiling.

6. **Conclusion**:
- Therefore, the water in the beaker can boil when the steam is at a low pressure. This is because the low pressure allows the water to reach its boiling point more quickly.

### Final Answer:
The water can boil when the steam is at low pressure.