Boiling water is changing into steam. Under this condition the specific heat of water is

Options

A. zero
B. one
C. Infinite
D. less than one

Explanation

To solve the question regarding the specific heat of water when it is boiling and changing into steam, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Process**: The question states that boiling water is changing into steam. This indicates a phase change from liquid (water) to gas (steam).

2. **Identify the Key Concept**: In a phase change, such as boiling, the temperature of the substance remains constant. This means that while the water is boiling, it does not increase in temperature until all of it has turned into steam.

3. **Use the Formula for Specific Heat**: The specific heat (C) can be defined using the formula:
\[ C = \frac{Q}{m \Delta T} \]
where:
- \( Q \) is the heat added,
- \( m \) is the mass of the substance,
- \( \Delta T \) is the change in temperature.

4. **Determine the Change in Temperature**: Since the boiling water is at a constant temperature during the phase change, the change in temperature (\( \Delta T \)) is zero.

5. **Substitute into the Formula**: Plugging in the values into the specific heat formula, we have:
\[ C = \frac{Q}{m \cdot 0} \]
Since \( \Delta T = 0 \), this leads to division by zero.

6. **Conclusion about Specific Heat**: In physics, division by zero is undefined, which in the context of specific heat means that the specific heat during a phase change is considered to be infinite.

7. **Select the Correct Option**: Among the given options (0, 1, infinite, less than 1), the correct answer is **infinite**.

### Final Answer:
The specific heat of water while it is boiling and changing into steam is **infinite**.