38. In a rotation photograph six layer lines are observed both above and below the
zero layer line. If the heights of these layer lines above (or below) the zero layer
are 0.29, 0.59, 0.91, 1.25, 1.65, and 2.2 cm, respectively. The camera radius is
3 cm and the wavelength of the X-ray is 1.54 Å, the cell height of the crystal
along the axis of rotation is:
(a) 18 Å
(b) 16 Å
(c) 14 Å
(d) 12 Å
39. In a rotation photograph, the separation of the fourth layer line from the zero
layer line is 2.2 cm. If the camera radius is 3 cm and the lattice parameter is 16
Å, the wavelength of the X-ray used is:
(a) 3.54 Å
(b) 2.54 Å
(c) 1.54 Å
(d) 0.54 Å
40. A simple cubic crystal is irradiated with X-rays of wavelength 0.9 Å at a
glancing angle. The crystal is rotated and the angles for Bragg reflections are
measured. The set of crystal planes will give the smallest angle for first-order
reflection is:
(a) {220}
(b) {111}
(c) {110}
(d) {100}
41. A simple cubic crystal is irradiated with X-rays of wavelength 0.9 Å at a
glancing angle. The crystal is rotated and the angles for Bragg reflections are
measured. If the glancing angle is 8.9°, angle for the first-order reflection from
the (110) crystal planes is:
(a) 12.62°
(b) 14.62°
(c) 16.62°
(d) 18.62°
42. An oscillation photograph is taken with CuKa radiation the rotation being
about an axis of length 7.2 Å. If the camera diameter is 57.3 mm, the distance
of the first layer line w.r.t zero layer is:
(a) 5.28 mm
(b) 6.28 mm
(c) 7.28 mm
(d) 8.28 mm
378
9 Determination of Crystal Structure Parameters