Predict whether the hottest part of a room will be near the ceiling, in the center, or near the floor, given that there is a hot-air vent near the floor.

near the ceiling

Explanation:

Air when heated expands, this means that that the density of air decreases. When the density decreases it rises up. Things of lesser density rise up. This could be understood by considering the case of water. Wood floats because it has less density when compared with water.

In this case all the hot air being pumped in the room will get accumulated at the top of the room, the hot air will not stay at the bottom. This means that the hottest part will be near the ceiling.

i think the answer is a, hope this is right, that would be my best guess.

photocells convert light energy to electricity