Assertion : When two positive point charges move away from each other, then their electrostatic potential energy decreases.
Reason : Change in potential energy between two points is equal to the work done by electrostatic forces.

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 correct explanation of Assertion.
C. If Assertion is true but Reason is false.
D. If Assertion is false but Reason is true.

Answer

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

### Step 1: Understand the Assertion
The assertion states: "When two positive point charges move away from each other, then their electrostatic potential energy decreases."

- **Explanation**: The electrostatic potential energy \( U \) between two point charges \( Q_1 \) and \( Q_2 \) separated by a distance \( r \) is given by the formula:
\[ U = \frac{k \cdot Q_1 \cdot Q_2}{r} \]
where \( k \) is Coulomb's constant. As the charges move away from each other, the distance \( r \) increases. Since \( U \) is inversely proportional to \( r \), as \( r \) increases, \( U \) decreases.

### Step 2: Understand the Reason
The reason states: "Change in potential energy between two points is equal to the work done by electrostatic forces."

- **Explanation**: This statement is a fundamental principle in electrostatics. The change in potential energy \( \Delta U \) when a charge moves in an electric field is equal to the work done \( W \) by the electrostatic forces. Mathematically, this can be expressed as:
\[ \Delta U = W \]

### Step 3: Evaluate the Assertion and Reason
- Both the assertion and reason are true statements.
- However, the reason does not directly explain the assertion. The assertion specifically discusses the behavior of potential energy as charges move apart, while the reason discusses the relationship between work done and change in potential energy in a more general context.

### Conclusion
Based on the analysis:
- The assertion is true.
- The reason is true.
- The reason is not the correct explanation of the assertion.

Thus, the correct answer is that both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

### Final Answer
**Option 2**: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

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