Arrange the following in decreasing order of their boiling points.
(A) n–butane
(B) 2–methylbutane
(C) n-pentane
(D) 2,2–dimethylpropane
(i) A > B > C > D
(ii) B > C > D > A
(iii) D > C > B > A
(iv) C > B > D > A
The answer is the option (iv) C > B > D > A
Explanation: We know that Boiling point α molar mass & Boiling point is α surface area.
It means that the boiling point will decrease on branching (surface area decreases on branching). Therefore, the highest boiling point is that of n-pentane and the lowest is of n-butane. The other two options have branches; therefore, 2-methyl butane has a higher boiling point than 2,2-dimethyl propane.