Which of the following represents a binary mixture having the same composition in liquid and vapour phase and boil at a constant temperature?

Azeotropes

Some liquids on mixing, form azeotropes which are binary mixtures having the same composition in liquid and vapour phase and boil at a constant temperature. In such cases, it is not possible to separate the components by fractional distillation. There are two types of azeotropes called minimum boiling azeotrope and maximum boiling azeotrope.