A narrow beam of x-rays with wavelength 1.5 a is reflected from an ionic crystal with an fcc lattice structure with a density of 3.32 gem". the molecular weight

A narrow beam of X-rays with wavelength 1.5 A is reflected from an ionic crystal with an fcc lattice structure with a density of 3.32 gem". The molecular weight is 108 AMUJ (1AMU = 1.66 x 10 g) A. The lattice constant is (a) 6.00 Å (b) 4.56 Å (c) 4.00 Å (d) 2.56 Å