The diagram shows the movement of air as a result of convection currents. at which

X

Hot air rises = it's less dense than cold air = falls

X

Explanation:

In the given diagram, air moves as a result of convection currents. The air at the bottom, near the space heater gets heated up. As temperature rises, the density of air reduces. It becomes less dense and rises up. The least dense is at W. As the air rises, it gets cooled and becomes more dense and heavier and thus, sinks down. The highest density of air would be at X.

b) 10 minutes

girls stopped for 10 minutes.