Experimentally,it was found that a metal oxide has the formula $M_{0.98}O$. The metal $M$ is present as $M^{2+}$ and $M^{3+}$ in its oxide. The fraction of the metal which exists as $M^{3+}$ would be: .................... $\%$

Which of the following defects is observed in steel?

Which of the following statements are not correct?
$(A)$ Diode is a combination of $n$-type and $p$-type semiconductors.
$(B)$ Silicon or germanium is electron rich impurity.
$(C)$ Phosphorus and arsenic are electron deficient impurities.
$(D)$ Schottky defect decreases the density of the crystal.

If $NaCl$ is doped with $10^{-4} \ mol \%$ of $SrCl_2,$ the concentration of cation vacancies will be $(N_A = 6.02 \times 10^{23} \ mol^{-1}).$

If molten $NaCl$ contains $SrCl_2$ as impurity,crystallization can generate

In $Schottky$ defect,.....