The pyknometric density of sodium chloride crystal is `2.165xx10^(3)kg m^(-3)` while its `X` ray density is `2.178xx10^(3)kg m^(-3)` the fraction of unoccupied sites in `NaCl` crystal is

Options

A. `5.97`
B. `5.97xx10^(-2)`
C. `5.97xx10^(-1)`
D. `5.97xx10^(-3)`

Answer

D

Explanation

Fraction of unoccupied sites
`=("X-ray density-pyknometric denstiy")/("X-ray density")`
`=(2.178xx10^3-2.165xx10^3)/(2.178xx10^3)=5.97xx10^(-3)`