Chapter 6 Multiple Choice Questions

. For the diffraction pattern from a simple cubic unit cell (with cell-side length 0.4 nm) in an experiment with X-rays of wavelength 0.154 nm, the first (lowest) angle of diffraction is predicted to occur at which of the following angles Θ?

5.1^o

11.1^o

22.2^o

13.7^o

. A diffraction pattern from a single cubic lattice gives the first (lowest) diffraction angle as 15.5^o in an experiment with incident X-rays of wavelength 0.154 nm. The corresponding cell length responsible for this diffracted beam is which of the following?

0.29 nm

29 nm

0.15 nm

2.3 nm

. For a simple (primitive) cubic unit cell, the values observed for sin²Θ for the diffraction pattern will be in the proportions of which of the following series of integers?

3 5 7 9 11 13

3 4 8 11 12 14

1 2 3 4 5 6 8

2 3 5 6 9 10 13

. For a simple cubic structure, picture the unit cell as a 'box' and identify the Miller indices of the ends (faces) of the box as which of the following?

2,0,0

1,1,1

1,0,1

1,0,0

. For a body-centred cubic structure, for which of the following pairs of planes does the atom at the centre of the cell lie in both of the planes, thus giving in-phase reflections?

1,0,0 and 1,1,0

1,1,0 and 1,1,1

1,1,0 and 2,0,0

1,1,1 and 2,0,0

. Which of the following represents the order of the extent of intensity of scattering of X-rays from the ions Na⁺, Li⁺, Cl^-, Br^-:

Na⁺ <Li⁺<Br^-<Cl^-

Br^-<Cl^-<Na⁺<Li⁺

Li⁺<Na⁺<Cl^-<Br^-

Li⁺<Cl^-<Na⁺<Br^-

. Which of the following sets of ratios of the integral values of sin²Θ would be expected for the diffraction pattern from caesium chloride, which is an interpenetrating pair of simple cubic lattices (with a caesium ion at the centre of a cube of chloride ions, and vice versa)?

3 4 8 11 12 (all strong)

1 2 3 4 5 (all strong)

3 (weak), 4 (strong), 8 (strong), 11 (weak)

1 (weak), 2 (strong), 3 (weak), 4 (strong), 5 (weak)

. The molecule PF₅ is believed to have a trigonal bipyramidal structure as shown below. How many separate internuclear distances will be revealed by an electron-diffraction study of the gaseous material?

1

3

6

5

. A gas-phase electron diffraction study of 1,2-dibromoethane is undertaken. The results indicate that one of the following is the preferred conformation: identify which you think this is.

A

B

C

D

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