5. In a plane hexagonal lattice with a = b = 3Å and u = 120°, a translation vector
is given by ~ t ¼ 2~ a þ 3 ~ b, its magnitude is:
(a) 6.94Å
(b) 7.94Å
(c) 8.94Å
(d) 9.94Å
6. In a plane hexagonal lattice with a = b = 3Å and u = 120°, a translation vector
is given by ~ t ¼ 2~ a þ 3 ~ b, its direction is:
(a) [1 2]
(b) [1 3]
(c) [2 2]
(d) [2 3]
7. In a square lattice with a = b = 3Å and u = 90°, a translation vector is given by
~ t ¼ 3~ a þ 4 ~ b, its magnitude is:
(a) 12.0Å
(b) 13.0Å
(c) 14.0Å
(d) 15.0Å
8. In a square lattice with a = b = 3Å and u = 90°, a translation vector is given by
~ t ¼ 3~ a þ 4 ~ b, its direction is:
(a) [3 1]
(b) [3 2]
(c) [3 3]
(d) [3 4]
9. In a simple orthorhombic crystal system, a = 2Å, b = 3Å and c = 4Å, two
lattice points are connected through a translation vector ~ T ¼ 2~ a þ 3 ~ b þ 4~ c, its
magnitude is:
(a) 16.80Å
(b) 17.80Å
(c) 18.80Å
(d) 19.80Å
1.5 Close Packing of Identical Atoms (Spheres)
35