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`