Assertion: Boiling point of pentane is higher than 2,2-dimethylpropane.
Reason: There is steady increase in boiling point with increase in molecular mass.

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

B

Explanation

Pentane and 2,2-dimethylpropane are isomers having same molecular formula. Pentane has high boiling point because it is straight chain isomer whereas 2,2-dimethylpropane is branched chain due to which the molecule attains the shape of a sphere. Thus, results in smaller area of contact and therefore weak intermolecular forces.