Assertion: Staggered conformation of ethane is most stable while eclipsed conformation is least stable. ltbr. Reason: Staggered form has the least torsional strain and the eclipsed form has the maximum torsional strain.

Options

A. If both assertion and reson are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

To solve the assertion-reason question regarding the stability of ethane's conformations, we will analyze both the assertion and the reason step by step.

### Step 1: Understanding the Assertion
The assertion states that the staggered conformation of ethane is the most stable, while the eclipsed conformation is the least stable.

- **Staggered Conformation**: In this arrangement, the hydrogen atoms on one carbon are positioned as far away as possible from the hydrogen atoms on the adjacent carbon. This minimizes the repulsion between the electron clouds of the hydrogen atoms, leading to a more stable configuration.

- **Eclipsed Conformation**: In this arrangement, the hydrogen atoms on one carbon are directly aligned with the hydrogen atoms on the adjacent carbon. This alignment causes increased repulsion between the electron clouds of the hydrogen atoms, resulting in a less stable configuration.

### Step 2: Understanding the Reason
The reason provided states that the staggered form has the least torsional strain, while the eclipsed form has the maximum torsional strain.

- **Torsional Strain**: This is the strain experienced by a molecule when there is an eclipsing interaction between atoms or groups on adjacent carbons. In the staggered conformation, the torsional angle is 60 degrees, which allows for the maximum distance between the hydrogen atoms, resulting in minimal torsional strain.

- In contrast, in the eclipsed conformation, the torsional angle is 0 degrees, which leads to maximum overlap of the electron clouds of the hydrogen atoms, resulting in maximum torsional strain.

### Step 3: Conclusion
Both the assertion and the reason are correct. The staggered conformation is indeed the most stable due to the least torsional strain, while the eclipsed conformation is the least stable due to maximum torsional strain.

### Final Answer
- **Assertion**: True
- **Reason**: True
- **Conclusion**: The reason correctly explains the assertion.