The specific heat of water is

Options

A. `1 "cal/g".^@C`
B. `"4.2 joule/g".^@C`
C. `"4200 joule/g".^@C`
D. all of the above

Answer

### Step-by-Step Solution:

1. **Understanding Specific Heat**:
- Specific heat is defined as the amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius (or one Kelvin).
- The formula for specific heat (c) can be expressed as:
\[ c = \frac{Q}{m \cdot \Delta T} \]
where \( Q \) is the heat added, \( m \) is the mass of the substance, and \( \Delta T \) is the change in temperature.

2. **Specific Heat of Water**:
- The specific heat of water is a well-known value. It is commonly accepted that the specific heat of water is:
\[ c = 1 \text{ calorie/g°C} \]
- This means that to raise the temperature of 1 gram of water by 1 degree Celsius, 1 calorie of heat is required.

3. **Conversion to Joules**:
- To convert calories to joules, we use the conversion factor:
\[ 1 \text{ calorie} = 4.2 \text{ joules} \]
- Therefore, the specific heat of water in joules is:
\[ c = 1 \text{ calorie/g°C} = 4.2 \text{ joules/g°C} \]

4. **Final Answer**:
- Hence, the specific heat of water can be expressed as:
\[ c = 4.2 \text{ joules/g°C} \]

### Conclusion:
The specific heat of water is **4.2 joules per gram per degree Celsius**.

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