If the air in a room has lower temperature than the air coming out of a floor vent from a forced air heater , heat would flow

From the air in the vent to the air in the room.

See explanation

Explanation:

According to the kinetic molecular theory, the molecules that compose a gas are in constant random motion.

The temperature of a gas is a measure of the average kinetic energy of the gas molecules.

When the balloon was placed in a hot water bath, the balloon becomes larger because the gas inside the balloon expands. This is because, more kinetic energy is supplied to the molecules of the gas hence they spread out.

When the balloon is placed in cold water, the kinetic energy of the gas molecules in the balloon decreases as temperature decreases hence the balloon shrinks