The second virial coefficient for water at 300k is reported as -1126 cm^3 *mol^-1. calculate the compression factor for gaseous water under these conditions using the virial equation (truncated after the second virial coefficient).

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?