Using an approach analogous to the development of Eq. (10.29) for nuclear reaction rates, make a crude estimate of the number of random collisions per cubic meter per second between CO and H2 molecules in a giant molecular cloud that has a temperature of 15 K and a number density of nH2=108 m−3. Assume (incorrectly) that the molecules are spherical in shape with radii of approximately 0.1 nm, the characteristic size of an atom.