A sealed 22.4L flask contains pure O2 at STP. A second sealed flask contains CH4 at STP. Which of the following statements concerning the molecules in the flasks is/are true? Please provide explanation.

1. The average kinetic energy of the O2 molecules is greater than the av. kinetic energy of the CH4 molecules

2. The av. velocity of the CH4 molecules is greater than the average velocity of the O2 molecules

3. The volume occupied by the gas molecules is small relative to the total volume of the flasks

A) 1 only
B) 2 only
C)3 only
D) 2 and 3
E) 1, 2, and 3.