A: For a certain amount of gas, PV is always constant at constant temperature.
R: On increasing temperature PV increases for fixed amount of ideal gas.

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 false statements, then mark (4)

Answer

To analyze the given statements, we will break down the assertion (A) and reason (R) step by step.

### Step 1: Understanding the Assertion (A)
The assertion states that "For a certain amount of gas, PV is always constant at constant temperature."

- **Explanation**: According to the ideal gas law, \( PV = nRT \), where:
- \( P \) = pressure
- \( V \) = volume
- \( n \) = number of moles of gas
- \( R \) = universal gas constant
- \( T \) = temperature

- If the temperature \( T \) is held constant, and since \( n \) (the amount of gas) and \( R \) (the gas constant) are also constants, it follows that \( PV \) must also be constant.

### Step 2: Understanding the Reason (R)
The reason states that "On increasing temperature, PV increases for a fixed amount of ideal gas."

- **Explanation**: If we increase the temperature \( T \) while keeping \( n \) constant, the equation \( PV = nRT \) indicates that \( PV \) will increase because \( R \) and \( n \) are constants. Therefore, an increase in \( T \) leads to an increase in \( PV \).

### Step 3: Evaluating the Relationship Between A and R
Now we need to determine if the reason (R) correctly explains the assertion (A).

- The assertion (A) is true: \( PV \) is constant at constant temperature.
- The reason (R) is also true: \( PV \) increases with an increase in temperature for a fixed amount of gas.

However, the reason does not explain the assertion because the assertion is specifically about the condition of constant temperature, while the reason discusses the effect of changing temperature.

### Conclusion
- Assertion (A) is true.
- Reason (R) is true, but it does not explain assertion (A).

Thus, the correct answer is that the reason does not correctly explain the assertion.

### Final Answer
The correct option is: 2 (Assertion is true, Reason is true but does not explain the Assertion).

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