In the following questions a statement of assertion (A) followed by a statement of reason (R) is given. Choose the correct option out of the choices given below each question.
Assertion (A) : Among isomeric pentanes, 2, 2-dimethylpentane has highest boiling point.
Reason (R) : Branching does not affect the boiling point.
(i) Both A and R are correct and R is the correct explanation of A.
(ii) Both A and R are correct but R is not the correct explanation of A.
(iii) Both A and R are not correct.
(iv) A is not correct but R is correct.
(iii) Both A and R are not correct.
Explanation – Long chain hydrocarbon have higher boiling point than branched chain.
If branching increases than it decrease the boiling point. Branching decreases the surface area of alkanes due to this force of attraction between the molecule decreases. If we apply heat in branch chain hydrocarbon molecule it will separate easily due low molecular attraction. So, branch chain molecule boil easily than long chain.