When NaCl is doped with 1.0×10−3 mole of SrCl2, the number of cation vacancy is ?
6.023×1018
6.023×1020
2×6.023×1020
3.011×1020
Two Na+ ions are replaced by one Sr2+ ions doped =1.0×10−3×6.02×1023=6.02×1020