Chapter 1, Problem 49P

Can you tell me if my answers are correct

Bunsenite (NiO) crystallizes like common salt (NaCl), with a lattice parameter a = 4.177 Å. A sample of this mineral that has Schottky defects that are not supposed to decrease the volume of the material has a density of 6.67 g/cm3. What percentage of NiO molecules is missing? (Data: atomic weight of Ni: 58.7; atomic weight of O: 16).

A sample of aluminum (face-centered cubic - FCC) has a density of 2.695 mg/m3 and a lattice parameter of 4.04958 Å. Calculate the fraction of vacancies in the structure. (Atomic weight of aluminum: 26.981).