What fraction (n/N) of the lattice sites are vacant at 298 K for a crystal in which the energy required to make a defect is 1 eV.`(1 eV = 1.602 xx 10^(-19) J)`

Explanation

If `E_upsilon` is the energy required to create one vacant site, then by Boltzmann formula
`n/N=e^(-E_upsilon //kT)` (k=Boltzmann constant =`R/N_0`)
or In `n/N=-E_upsilon / "kT"`
or log `n/N=- E_upsilon / "2.303 kT"=(1.602xx10^(-19))/(2.303(8.314//6.023xx10^23)xx298)`
`=-0.00169185xx10^4 =-16.9185=bar(17).0815`
`n/N`=Antilog `bar(17).0815=1.206xx10^(-17)`