Assertion: Cyclobutane is less stable than cyclopentane
Reason : The bond angles in cyclobutane and cyclopentane are `90^@` and `108^@`, respectively

Options

A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
B. Both Assertion and Reason are true but Reason is not a correct explanation of Assertion
C. Assertion is true but Reason is false
D. Assertion is false but Reason is true

Explanation

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

### Step 1: Understand the Assertion
The assertion states that "Cyclobutane is less stable than cyclopentane."

- **Explanation**: Cyclobutane is a four-membered ring, while cyclopentane is a five-membered ring. Generally, larger rings tend to be more stable due to less angle strain.

### Step 2: Understand the Reason
The reason states that "The bond angles in cyclobutane and cyclopentane are 90° and 108°, respectively."

- **Explanation**: The bond angle in cyclobutane is 90°, which is significantly less than the ideal tetrahedral angle of 109.5°. This creates angle strain. In contrast, cyclopentane has a bond angle of 108°, which is closer to the ideal angle and thus experiences less angle strain.

### Step 3: Analyze the Relationship
Now, we need to connect the assertion and the reason.

- **Analysis**: The lower bond angle in cyclobutane (90°) leads to greater internal strain compared to the bond angle in cyclopentane (108°). This internal strain is inversely related to stability; therefore, cyclobutane, having a higher internal strain, is less stable than cyclopentane.

### Step 4: Conclusion
Both the assertion and reason are true, and the reason correctly explains the assertion.

### Final Answer
Both the assertion and reason are true, and the reason is the correct explanation of the assertion.

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