Assertion Straight line on V-T graph represents isobaric process.
Reason If V `prop` T, then p= constant i.e., orocess is isobaric.

Options

A. If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
B. If both Assertion and Reason are correct but Reason is not the correct explation os Assertion.
C. If Assertionis true bur Reason is false.
D. If Assertion is false but Reason is true.

Explanation

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

**Assertion:** A straight line on the V-T graph represents an isobaric process.

**Reason:** If V is proportional to T, then P = constant, i.e., the process is isobaric.

### Step-by-Step Solution:

1. **Understanding the V-T Graph:**
- The V-T graph plots volume (V) on the y-axis and temperature (T) on the x-axis.
- For an isobaric process (constant pressure), the relationship between volume and temperature can be derived from the ideal gas law, \( PV = nRT \).

2. **Analyzing the Assertion:**
- A straight line on the V-T graph indicates a linear relationship between volume and temperature.
- For a process to be isobaric, the equation \( V = \frac{nR}{P} T \) must hold true, where \( n \) and \( R \) are constants.
- If pressure (P) is constant, then the equation represents a straight line that passes through the origin (0,0).

3. **Checking if the Straight Line Passes Through the Origin:**
- If the straight line does not pass through the origin, it indicates that the pressure is not constant throughout the process.
- Therefore, the assertion that a straight line on the V-T graph represents an isobaric process is **false** unless it passes through the origin.

4. **Analyzing the Reason:**
- The reason states that if \( V \propto T \), then \( P \) must be constant.
- This is derived from the relationship \( V = \frac{nR}{P} T \). If \( n \) and \( R \) are constants, and \( V \) is proportional to \( T \), then \( P \) must indeed be constant.
- Thus, the reason is **true**.

5. **Conclusion:**
- Since the assertion is false and the reason is true, we conclude that the correct option is that the assertion is false, and the reason is true.

### Final Answer:
- **Assertion:** False
- **Reason:** True