Question

Professor Askew has a beach ball in his office which displays the map of the cosmic microwave background as observed by the WMAP experiment. This ball is full of atmosphere and has a volume of...

about 0.5 cubic meters. For our purposes, we can treat the ball like it is full of nitrogen (N2).

If some joker replaces the gas in the ball with hydrogen (H2) at the same pressure and temperature, then how does the internal energy of the ball change? How do the velocities of the molecules within in the ball change?