Assertion: Among isomeric pentanes, 2,2-dimethylpropane has the highest boiling point.
Reason: Branching does not affect the boiling point.
1. Both assertion and reason are true and the reason is the correct explanation of assertion.
2. Both assertion and reason are true and the reason is not the correct explanation of assertion.
3. Both assertion and reason are not correct
4. Assertion is false but the reason is true.
Hint: Boiling point is inversely proportional to branching
As branching increases, the boiling point of alkane decreases in comparable molecular masses. The structures of pentane and 2,2-dimethylpropane are as follows:
As branching increases the boiling point of the compound decreases but in compounds with comparable molar masses. Hence, 2,2-dimethylpropane boiling point is lower than pentane because it has a higher branching than pentane.
Thus, both assertion and reason are not correct.