A gas is enclosed in a cylindrical piston. When the gas is heated from 0C to 100C, the piston is allowed to move to maintain a constant pressure. According to the Kinetic-Molecular Theory of Matter
(A) the mass of the gas will increase
(B) the number of molecules of gas must increase
(C) the size of the individual molecules has increased
(D) the average speed of the molecules has increased
(E) the molecules continue to strike the sides of the container with the same energy
