Assertion : The heat of neutralisation for a strong acid and a weak base is always equal to -57.1 kJ.
Reason : One gram equivalent of a strong acid always neutralises one gram equivalent of a weak base.

Options

A. If both Assertion and Reason are CORRECT and Reason is the CORRECT explanation of the Assertion.
B. If both Assertion and Reason are CORRECT but Reason is not the CORRECT explanation of the Assertion.
C. If Assertion is CORRECT but Reason is INCORRECT.
D. If Assertion is INCORRECT but Reason is CORRECT.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that "The heat of neutralization for a strong acid and a weak base is always equal to -57.1 kJ."

- The heat of neutralization is the heat change that occurs when an acid reacts with a base to form water and a salt.
- For strong acids and strong bases, the heat of neutralization is typically around -57.3 kJ/mol.
- However, when a strong acid reacts with a weak base, the heat of neutralization is not exactly -57.1 kJ because some energy is used to ionize the weak base.

**Conclusion for Step 1:** The assertion is incorrect.

### Step 2: Understand the Reason
The reason states that "One gram equivalent of a strong acid always neutralizes one gram equivalent of a weak base."

- This statement is true. One gram equivalent of a strong acid will indeed neutralize one gram equivalent of a weak base.
- The concept of equivalents in acid-base reactions is based on the number of moles of H⁺ ions provided by the acid and the number of moles of OH⁻ ions provided by the base.

**Conclusion for Step 2:** The reason is correct.

### Step 3: Analyze the Relationship Between Assertion and Reason
The assertion is incorrect, while the reason is correct. However, the reason does not explain the assertion because the heat of neutralization for a strong acid and a weak base is not equal to -57.1 kJ due to the energy required for ionization of the weak base.

### Final Conclusion
- Assertion: Incorrect
- Reason: Correct
- The reason does not adequately explain the assertion.

### Final Answer
The assertion is false, and the reason is true, but the reason does not explain the assertion.

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