Define azeotropic mixture.

Explanation

A liquid mixture which boils at a constant temperature without any change in its composition is called an azeotropic solution or azeotrope.
Maximum boiling azeotrope : Mixture of 80% `H_2 O & 20% `HCI (b.p. = `108^@ C`)
Minimum boiling azeotrope : Mixture of 94.5% `C_2 H_5 OH & 4.5% H_2O ` (b.p. = `78.5&^@ C)`