Rank the following alkanes in order of decreasing boiling point,putting the alkane with the highest boiling point first.
A)I II III
B)I III II
C)II III I
D)III II I

Question

Rank the following alkanes in order of decreasing boiling point,putting the alkane with the highest boiling point first. 
A)I > II > III 
B)I > III > II 
C)II > III > I 
D)III > II > I

Quizplus · Accepted Answer

The boiling point of an alkane depends on its molecular weight and shape. Branched alkanes have lower boiling points than their straight-chain isomers because the branching decreases the surface area, reducing intermolecular forces. Therefore, III, with its three branches, will have the lowest boiling point, followed by I, with two branches, and finally II, the straight-chain alkane, with the highest boiling point. Therefore, the correct order is I > III > II, which is option B.

Rank the Following Alkanes in Order of Decreasing Boiling Point,putting