37
MCQ (Single Correct Answer)
Which of the following represents correct order of conductivity in solids?
A
$\kappa_{\text {metals }}>>\kappa_{\text {insulators }}<\kappa_{\text {semiconductors }}$
B
$\kappa_{\text {metals }}<<\kappa_{\text {insulators }}<\kappa_{\text {semiconductors }}$
C
$\kappa_{\text {metals }}$., $\kappa_{\text {semiconductors }}>\kappa_{\text {insulators }}=$ zero
D
$\kappa_{\text {metals }}<\kappa_{\text {semiconductors }}>\kappa_{\text {insulators }} \neq$ zero
38
MCQ (Multiple Correct Answer)
Which of the following is not true about the voids formed in 3 dimensional hexagonal close packed structure?
A
A tetrahedral void is formed when a sphere of the second layer is present above triangular void in the first layer
B
All the triangular voids are not covered by the spheres of the second layer
C
Tetrahedral voids are formed when the triangular voids in the second layer lie above the triangular voids in the first layer and the triangular shapes of these voids do not overlap
D
Octahedral voids are formed when the triangular voids in the second layer exactly overlap with similar voids in the first layer
39
MCQ (Multiple Correct Answer)
The value of magnetic moment is zero in the case of antiferromagnetic substances because the domains ........... .
A
get oriented in the direction of the applied magnetic field
B
get oriented opposite to the direction of the applied magnetic field
C
are oppositely oriented with respect to each other without the application of magnetic field
D
cancel out each other's magnetic moment
40
MCQ (Multiple Correct Answer)
Which of the following statements are not true?
A
Vacancy defect results in a decrease in the density of the substance
B
Interstitial defects results in an increase in the density of the substance
C
Impurity defect has no effect on the density of the substance
D
Frenkel defect results in an increase in the density of the substance
41
MCQ (Multiple Correct Answer)
Which of the following statements are true about metals?
A
Valence band overlaps with conduction band
B
The gap between valence band and conduction band is negligible
C
The gap between valence band and conduction band cannot be determined
D
Valence band may remain partially filled