Most full scuba tanks have a pressure of between 1,800 p.s.i. and 3,000 p.s.i. (pounds per square inch). Approximately 70 to 85 cubic feet of air has been squeezed into the tank. When a diver takes his air tank to be refilled, the dive shop will hook his tank to a compressor with a pressure hose and place his tank in a tub of water while it is being filled. What reasons can you give for placing the tank in water? While thinking about this, keep the gas laws in mind. Explain your answer in detail.