Question

Arrange the following in decreasing order of their boiling points:

(I) n-Butane (II) 2-Methylbutane

(III) n-Pentane (IV) 2,2- Dimethylpropane

• A. I>II>III>IV
• B. II>III>IV>I
• C. IV>III>II>I
• D. III>II>IV>I

Answer 1

Answer: (D)

III>II>IV>I

Answer 2

: Boiling point of alkanes increases with increase in molecular mass and for the same alkane the boiling point decrease with branching.

Thus, the decresing order of their boiling points :

N-pentane >2- Methlbytane > 2,2

(III) (II)

Dimethylpropane > n-Butane

(IV) (I)