Genevieve and Alden each filled a plastic jug half-full of room temperature water. Genevieve put her jug on a sunny windowsill. Alden put his jug in a cool cupboard. After two hours, what did they observe?

After two hours, it is observed that Genevieve's Jar has less water than that of Alden.

Explanation:

The water in Genevieve's Jar didn't disappear. It was not drunk by the birds, it simply evaporated. Evaporation is what happens to liquid when they are heated. Water has three states: Solid (that is Ice), Liquid (that is the water which was put in the jar), and gas (vapor).

When water is exposed to heat sources like the sun, its molecules vibrate faster and escape into the atmosphere in form of vapor if the container has an opening.

When this happens for a prolonged period of time, the amount of water in the jar or container becomes less and less in volume.

This is not the case for the jar that was stored in a cool place where the water molecules remained stable.

Cheers