26
MCQ (Single Correct Answer)
In which of the following structures coordination number for cations and anions in the packed structure will be same?
A
$\mathrm{Cl}^{-}$ions form fcc lattice and $\mathrm{Na}^{+}$ions occupy all octahedral voids of the unit cell
B
$\mathrm{Ca}^{2+}$ ions form fcc lattice and $\mathrm{F}^{-}$ions occupy all the eight tetrahedral voids of the unit cell
C
$\mathrm{O}^{2-}$ ions form fcc lattice and $\mathrm{Na}^{+}$ions occupy all the eight tetrahedral voids of the unit cell
D
$\mathrm{S}^{2-}$ ions form fcc lattice and $\mathrm{Zn}^{2+}$ ions go into alternate tetrahedral voids of the unit cell
27
MCQ (Single Correct Answer)
What is the coordination number in a square close packed structure in two dimensions?
A
2
B
3
C
4
D
6
28
MCQ (Single Correct Answer)
Which kind of defects are introduced by doping?
A
Dislocation defect
B
Schottky defect
C
Frenkel defect
D
Electronic defect
29
MCQ (Single Correct Answer)
Silicon doped with electron rich impurity forms ............ .
A
$p$-type semiconductor
B
n-type semiconductor
C
intrinsic semiconductor
D
insulator
30
MCQ (Single Correct Answer)
Which of the following statements is not true?
A
Paramagnetic substances are weakly attracted by magnetic field
B
Ferromagnetic substances cannot be magnetised permanently
C
The domains in antiferromagnetic substances are oppositely oriented with respect to each other
D
Pairing of electrons cancels their magnetic moment in the diamagnetic substances