Rank the following alkanes in order of increasing boiling point.
A)I II III IV
B)IV III II I
C)II III IV I
D)IV III I II

Question

Rank the following alkanes in order of increasing boiling point. 
A)I > II > III > IV 
B)IV > III > II > I 
C)II > III > IV > I 
D)IV > III > I > II

Quizplus · Accepted Answer

The boiling point of an alkane depends on its molecular weight and the strength of intermolecular forces. 
IV has the highest molecular weight, followed by III, II, and I. 
All the given alkanes are straight chain, so branching (which would decrease intermolecular forces) is not a factor here. 
Therefore, IV has the highest boiling point and I has the lowest, resulting in the rank of IV > III > II > I, which is option B.

Rank the Following Alkanes in Order of Increasing Boiling Point