43. A unit cell of NaCl has four formula units. If the side of the unit cell is 5.64 Å,
its density is:
(a) 1965 kg/m
3
(b) 2065 kg/m
3
(c) 2165 kg/m
3
(d) 2265 kg/m
3
44. Sodium chloride has fcc structure. Its density is 2:18 Â 10
3
kg=m
3 , the atomic
weight of sodium and chlorine are 23 and 35.5, respectively. The interatomic
separation is:
(a) 5.81 Â 10
−10 m
(b) 4.81 Â 10
−10 m
(c) 3.81 Â 10
−10 m
(d) 2.81 Â 10
−10 m
45. Potassium chloride has density of 1:98 Â 10
3
kg=m
3 and its molecular weight is
74.55. Its interatomic separation is:
(a) 7.30 Â 10
−10 m
(b) 6.30 Â 10
−10 m
(c) 5.30 Â 10
−10 m
(d) 4.30 Â 10
−10 m
46. The nearest neighbor distance in a silver crystal is 2.87 Å. Silver crystallizes in
fcc form, its density is:
(a) 1.068 Â 10
4 kg/m
3
(b) 2.068 Â 10
4 kg/m
3
(c) 3.068 Â 10
4 kg/m
3
(d) 4.068 Â 10
4 kg/m
3
47. a-iron belongs to a bcc structure. The density of a-iron is 7860 kg=m
3 and its
atomic weight is 55.85. Radius of the iron atom is:
(a) 3.24 Å
(b) 2.24 Å
(c) 1.24 Å
(d) 0.24 Å
48. Zinc has hcp structure. The height of the unit cell is 4.94 Å, the nearest
neighbor distance is 2.7 Å and the at. Wt. of zinc is 65.38. The density of zinc
is:
(a) 3961 kg/m
3
(b) 4961 kg/m
3
(c) 5961 kg/m
3
(d) 6961 kg/m
3
9.1 Steps in Crystal Structure Determinations
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