Schottky defect.

The number of Schottky defects (n) present in an ionic compound containing N ions at temperature T is given by n = Ne^(-E//2KT) , where E is the energy required to create n Schottky defects and K is the Boltzmann constant, If the mole fraction of Schottky defect in NaCl crystal at 2900 K is X , then calculate -ln(x) , Given: DeltaH of Schottky defect = 2 eV and K = 1.38 xx 10^(-23) J K^(-1) 1 eV = 1.608 xx 10^(-19) J