Question

Isomers of hexane, based on their branching, can be divided into three distinct classes as shown in the figure.The correct order of their boiling point is(a) I > II > III (b) III > II > I(c) II > III > I (d) III > I > II

Answer 1

The correct order of the boiling point of the three distinct classes of isomeric hexane is III>II>I

• The boiling point of a substance is directly proportional to the surface area occupied by the molecules of the substance.
• Greater surface area increases the inter-molecular interaction between the molecules leading to increase in boiling point.
• The surface area of a molecule decreases with increase in branching, hence greater the branching lower is the boiling point.