There are four equal-sized bowls with equal amounts of milk. Bowl A is covered, and the milk is at room temperature. Bowl B is uncovered, and the milk is warmer than room temperature. Bowl C is uncovered, and the milk is cooler than room temperature. Bowl D is uncovered, and the milk is at room temperature. Which bowl has the highest vapor pressure?

Vapour pressure is the pressure exerted by vapour molecules over a liquid surface.

The vapour pressure is a property

a) inter molecular forces: higher the inter molecular forces lower the vapour pressure, In this case we have taken same liquid (milk) hence in all case the inter molecular forces will be same.

b) Temperature: higher the temperature higher the kinetic energy of molecules and more the tendency of liquid molecules to convert to vapor phase.

The vapor pressure will be independent of the container being closes or open.

Thus vapor pressure will be high in Bowl B which is uncovered, and the milk is warmer than room temperature, as it has higher temperature than all other bowl of milk.