Impurity Defects arises when foreign atoms are present at the lattice site in place of the host atom. For example in the molten state, NaCl contains small amount of `SrCl_2` in the form of impurity in the crystal Due to the presence of `SrCl_2` some site of `Na^(+)` ion is occupied by `Sr^(2+)`. For maintaining the neutrality of the crystal one `Sr^(2+)` replaces two ions of Nat and the remaining one site of `Na^(+)` will be vacant.

If NaCl is doped with `10^(-4)` mole percent of `SrCl_2`, the concentration of cation vacancies will be:

Options

A. `6.022 xx 10^16 mol^(-1)`
B. `6.022 xx 10^17 mol^(-1)`
C. `6.022 xx 10^14 mol^(-1)`
D. `6.022 xx 10^15 mol^(-1)`

Answer

B

Explanation

Doping by each `Sr^(2+)` ion will create one cation vacancy
`:.` concentration of cation vacancies
` = 6.022 xx 10^(23) xx (10^(-14))/(100)`
` = 6.022 xx 10^(17) mol^(-1)`