A : The potential energy of a system increases when work is done by conservative force.
R : Kinetic energy can change into potential energy and vice-versa.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are falsė statements, then mark (4).

Answer

To analyze the statements given in the question, we will break down each statement and evaluate their correctness step by step.

### Step 1: Analyze Statement A
**Statement A:** The potential energy of a system increases when work is done by conservative force.

- **Explanation:** A conservative force is defined as a force for which the work done is independent of the path taken and depends only on the initial and final positions. When work is done against a conservative force (like gravity), energy is stored in the system as potential energy. For example, lifting an object to a height \( h \) against gravity requires work equal to \( W = mgh \), which is stored as gravitational potential energy. Therefore, this statement is correct.

### Step 2: Analyze Statement R
**Statement R:** Kinetic energy can change into potential energy and vice-versa.

- **Explanation:** Kinetic energy (KE) is the energy of an object due to its motion, while potential energy (PE) is the energy stored in an object due to its position or configuration. In a closed system, energy can transform from one form to another. For instance, when an object is thrown upwards, its kinetic energy decreases as it rises, and its potential energy increases until it reaches its maximum height. Conversely, as it falls, potential energy is converted back into kinetic energy. Hence, this statement is also correct.

### Conclusion
Both statements A and R are correct.

### Final Answer
- **Statement A is correct.**
- **Statement R is correct.**