31. The atomic density (i.e., the number of atoms/area) in (110) plane of a bcc iron
with a = 2.87 Å is:
(a) 1.72 Â 10
19
(b) 2.72 Â 10
19
(c) 3.72 Â 10
19
(d) 4.72 Â 10
19
32. The atomic density (i.e., the number of atoms/area) in (111) plane of a bcc iron
with a = 2.87 Å is:
(a) 6.0 Â 10
19
(b) 7.0 Â 10
19
(c) 8.0 Â 10
19
(d) 9.0 Â 10
19
33. The atomic density (i.e., the number of atoms/area) in (100), plane of fcc
aluminum with a = 4.05 Å is:
(a) 4.22 Â 10
19
(b) 3. 22 Â 10
19
(c) 2. 22 Â 10
19
(d) 1. 22 Â 10
19
34. The atomic density (i.e., the number of atoms/area) in (110) plane of fcc aluminum with a = 4.05 Å is:
(a) 6.62 Â 10
18
(b) 7.62 Â 10
18
(c) 8.62 Â 10
18
(d) 9.62 Â 10
18
35. The atomic density (i.e., the number of atoms/area) in (111) plane of fcc aluminum with a = 4.05 Å is:
(a) 1.41 Â 10
19
(b) 2.41 Â 10
19
(c) 3.41 Â 10
19
(d) 4.41 Â 10
19
36. The atomic density (i.e., the number of atoms/area) in (0001) plane of an hcp
zinc with a = b = 2.66 Å and c = 4.95 Å is:
(a) 9.16 Â 10
18
(b) 8.16 Â 10
18
(c) 7.16 Â 10
18
(d) 6.16 Â 10
18
3.6 Packing Efficiency
133