Which of the following binary systems is an example of a maximum boiling azeotrope ?

ANS:A - Water-hydrochloric acid.

Among the options provided, the binary system "Water-Ethyl alcohol" is an example of a maximum boiling azeotrope. In a maximum boiling azeotrope, the boiling point of the mixture is higher than the boiling point of either pure component. For the water-ethyl alcohol system, the azeotropic mixture has a higher boiling point than the boiling points of pure water and pure ethyl alcohol. At a composition of approximately 95.6% ethanol and 4.4% water by mass, this azeotropic mixture boils at around 78.2°C. This phenomenon occurs due to the formation of hydrogen bonds between water and ethanol molecules, which alters the vapor pressure of the mixture, resulting in a maximum boiling azeotrope. So, the correct option is "Water-ethyl alcohol."