a-Sn (exists below 13.2 .C) has a cubic structure with lattice parameter a= 6.4912 A and a density of 5.769 g/cc (at 0 "C). B-Sn has a tetragonal crystal structure with lattice parameter a. = 5.8316 A, c = 3.1813 A and a density of 7365 g cc (at 30 .C). Determine the number of atoms per unit cell for both a-Sn and B-Sn and hence determine the percentage volume change that would occur when a-Sn is heated from 0'C to 30"C? The atomic weight of Sn is 118.69 g mol [5]