In scuba diving circles an 80 refers to a scuba tank that holds 80 cubic feet of air, a standard amount for recreational diving. Given that a scuba tank is a cylinder 2 feet long and half foot in diameter, determine (a) the volume of a tank and (b) the pressure in a tank when 80 cubic feet of air is compressed into its relatively small volume. (c) What is the mass of air in a tank that holds 80 cubic feet of air. Assume the temperature is 21 C and that the walls of the tank are of negligible thickness.