In the Schottky defect,

Use the appropriate symbols $T$ (True) or $F$ (False) for the following statements regarding defects in solids:
$(1)$ Frenkel defect arises due to the arrangement of cations and anions with a very small difference in size.
$(2)$ Frenkel defect can be called a dislocation defect.
$(3)$ $F$-centers arise due to the migration of electrons released from metal atoms into the crystal lattice.
$(4)$ Physical properties of the crystal do not change due to 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

$1 \ \text{mole}$ of $NaCl$ is doped with $10^{-5} \ \text{mole}$ of $SrCl_{2}$. The number of cationic vacancies in the crystal lattice will be:

Identify the incorrect statement regarding crystals having $Frenkel$ defect.

Explain the following term with a suitable example:
$(iv)$ $F$-centres