An approximate canonical partition function Q(N, V, T) of a gas is given by: Q(N, V, T) = 1N! × (2πmkBTh2)3N/2 × (V - Nb)N The thermal equation of state for this gas is given by (where b is a parameter independent of volume):

The average energy of an ensemble of noninteracting particles is 1000 kBT at temperature T. Each particle can have energy of either 0 or kBT. The number of particles in the ensemble is closest to (where kB is the Boltzmann constant):

Two conformations, A and B, of a single molecule have energies 5kBT and 9kBT, respectively, at a temperature T. Assuming a Boltzmann distribution, what is the fraction of molecules present in conformation B?