31
MCQ (Single Correct Answer)
Which of the following is not true about the ionic solids?
A
Bigger ions form the close packed structure
B
Smaller ions occupy either the tetrahedral or the octahedral voids depending upon their size
C
Occupation of all the voids is not necessary
D
The fraction of octahedral or tetrahedral voids occupied depends upon the radii of the ions occupying the voids
32
MCQ (Single Correct Answer)
A ferromagnetic substance becomes a permanent magnet when it is placed in a magnetic field because .......... .
A
all the domains get oriented in the direction of magnetic field
B
all the domains get oriented in the direction opposite to the direction of magnetic field
C
domains get oriented randomly
D
domains are not affected by magnetic field
33
MCQ (Single Correct Answer)
The correct order of the packing efficiency in different types of unit cells is ............ .
A
fcc $<$ bcc $<$ simple cubic
B
fcc $>$ bcc $>$ simple cubic
C
fcc $<$ bcc $>$ simple cubic
D
$\mathrm{bcc}<\mathrm{fcc}>$ simple cubic
34
MCQ (Single Correct Answer)
Which of the following defects is also known as dislocation defect?
A
Frenkel defect
B
Schottky defect
C
Non-stoichiometric defect
D
Simple interstitial defect
35
MCQ (Single Correct Answer)
In the cubic close packing, the unit cell has ............. .
A
4 tetrahedral voids each of which is shared by four adjacent unit cells
B
4 tetrahedral voids within the unit cell
C
8 tetrahedral voids each of which is shared by four adjacent unit cells
D
8 tetrahedral voids within the unit cells