The energy required to create a lattice vacancy in a crystal is equal to i ev. the ratio of the number densities of vacancies n(1200 k)/n(300 k) when the crysta

The energy required to create a lattice vacancy in a crystal is equal to I eV. The ratio of the number densities of vacancies n(1200 K)/n(300 K) when the crystal is at equilibrium at 1200 K and 300 K, respectively, is approximately (a) expl-30) (b) expl-15) ()exp(15) (d) exp(30)