If you wanted to make a scale model of air at 0.0 C and 1.00 atm, using

Question:

If you wanted to make a scale model of air at 0.0 °C and 1.00 atm, using ping-pong balls (diameter, 3.75 cm) to represent the N2 molecules (diameter, 0.30 nm),
(a) How far apart on average should the ping-pong balls be at any instant?
(b) How far would a ping-pong ball travel on average before colliding with another?