In which of the following is impurity defect observed?

Which among the following solids shows Frenkel defect?

Identify the defect developed when an ion of an ionic compound is missing from its regular site and occupies an interstitial position between lattice points.

Which of the following is $NOT$ true for Schottky defect?

In the Schottky defect,

$A$ silicon specimen is made into a $p-$type semiconductor by doping,on an average,one indium atom per $5 \times 10^7$ silicon atoms. If the number density of atoms in the silicon specimen is $5 \times 10^{28} \ \text{atoms} \ m^{-3}$,then the number of acceptor atoms in silicon per cubic centimeter will be