• Among the given liquids ether has a minimum boiling point which means ether is the most volatile one amongst the given liquids.

• And as the vapour pressure is the pressure exerted by the molecules of a liquid at liquid-vapour Equilibrium, the more volatility of a liquid indicates that the gaseous molecules will outnumber the liquid molecules which is a clear indication in more vapour pressure . hence amongst the given liquids ether will exert the greatest vapour pressure and water will have the lowest vapour pressure and the increasing order will be in accordance with fact :

(ii) Water < acetone < ether