Assertion : The normal boiling point of water is `100 C^(@)` and standard boiling point of water is `99.6 C^(@)` .
Reason : The temperature at which vapour pressure of liquid is equal to the external pressure is called boiling temperature at that pressure .

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion .
B. If both assertion and reason are true but reason is not the correct explanation of assertion .
C. If assertion is true but reason is false .
D. If both assertion and reason are false .

Explanation

To solve the assertion and reason question regarding the boiling point of water, we will break down the assertion and reason step by step.

### Step 1: Understand the Assertion
The assertion states that:
- The normal boiling point of water is 100°C.
- The standard boiling point of water is 99.6°C.

**Explanation**:
- The normal boiling point is defined as the boiling point of a liquid at 1 atmosphere (atm) of pressure. For water, this is 100°C.
- The standard boiling point is defined at a pressure of 1 bar, which is slightly less than 1 atm. For water, this is 99.6°C.

### Step 2: Understand the Reason
The reason states that:
- The temperature at which the vapor pressure of a liquid equals the external pressure is called the boiling temperature at that pressure.

**Explanation**:
- This is a correct definition of boiling point. Boiling occurs when the vapor pressure of the liquid equals the surrounding atmospheric pressure.

### Step 3: Analyze the Relationship
Now we need to analyze whether the reason correctly explains the assertion:
- Both the assertion and reason are true statements.
- However, the reason does not specifically explain why the standard boiling point (99.6°C) is lower than the normal boiling point (100°C). It merely defines boiling point without addressing the difference in boiling points due to pressure variations.

### Step 4: Conclusion
Based on the analysis:
- Both the assertion and reason are true.
- The reason is not the correct explanation for the assertion.

### Final Answer
The correct option is **B**: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

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