21
MCQ (Single Correct Answer)
The total number of tetrahedral voids in the face centred unit cell is .......... .
A
6
B
8
C
10
D
12
22
MCQ (Single Correct Answer)
Which of the following point defects are shown by $\mathrm{AgBr}(\mathrm{s})$ crystals?
1. Schottky defect
2. Frenkel defect
3. Metal excess defect
4. Metal deficiency defect
A
1 and 2
B
3 and 4
C
1 and 3
D
2 and 4
23
MCQ (Single Correct Answer)
In which pair most efficient packing is present?
A
hcp and bcc
B
hcp and ccp
C
bcc and ccp
D
bcc and simple cubic cell
24
MCQ (Single Correct Answer)
The percentage of empty space in a body centred cubic arrangement is ........... .
A
74
B
68
C
32
D
26
25
MCQ (Single Correct Answer)
Which of the following statement is not true about the hexagonal close packing?
A
The coordination number is 12
B
It has $74 \%$ packing efficiency
C
Tetrahedral voids of the second layer are covered by the spheres of the third layer
D
In this arrangement spheres of the fourth layer are exactly aligned with those of the first layer