An underwater diver breathes air from a scuba cylinder.
The cylinder has a volume of 10 litres10\text{ litres}10 litres and contains air compressed to 150 times normal atmospheric pressure. The air is released to the diver at normal atmospheric pressure. The diver consumes air at a rate of 12 litres12\text{ litres}12 litres per minute (measured at normal atmospheric pressure).
Calculate the maximum duration (in minutes) that the diver can breathe under water using this cylinder.
As the diver breathes out, air bubbles are released and rise toward the surface. Explain why these bubbles expand as they rise.