Consider a system of N non-interacting electrons at absolute zero of temperature. Assume that electrons follow the dispersion relation is constant. Among the ==k, where k is wave vector and following options which is/are correct? Fermi energy varies as N and N3/2 for 3 and 2 dimensions respectively. Fermi energy varies as N and N2/3 for 3 and 2 dimensions respectively. The ratio of pressure to energy density is 3/2 for two-dimensions The ratio of ground state energy per electron to Fermi energy is for three-dimensions.