Assertion: Chemical formula of n-propane and isopropane is the same.

Reason: n-propane doesn’t exhibit chain isomerism

A. Both Assertion and Reason are correct and Reason is correct explanation for Assertion

B. Both Assertion and Reason are correct But the Reason is not the correct explanation for Assertion

C. Assertion is incorrect but Reason is correct

D. Both Assertion and Reason are correct

Explanation:

1. Assertion: True.
   • Both n‑propane (straight-chain) and the so-called "isopropane" share the chemical formula C₃H₈. In fact, "isopropane" as a distinct isomer doesn't exist for propane—so they effectively have the same formula and structure.
2. Reason: True.
   • Chain isomerism requires at least four carbon atoms. With only three carbons, propane has no alternative chain structure and thus cannot exhibit chain isomerism.
3. Connection: The reason accurately explains the assertion. Because propane has only three carbons and no branching is possible, there’s essentially only one structure—making both compounds one and the same. Hence, R correctly justifies A.

Final Answer:

Assertion: Correct — n-propane and so-called isopropane have the same formula, C₃H₈.

Reason: Correct — propane cannot exhibit chain isomerism due to having only three carbon atoms.

Relationship: The Reason explains the Assertion accurately.

Correct Option: A