The impurity atoms which are mixed with pure silicon to make a $P$-type semiconductor are those of:

Which of the following statements is true for an $N$-type semiconductor?

At a temperature of $500 \ K$,the intrinsic electron number density $(n_e)$ and hole number density $(n_h)$ in a pure semiconductor are equal to $1.5 \times 10^{16} \ m^{-3}$. Now,by adding indium impurity,the hole density $(n_h)$ increases to $4.5 \times 10^{22} \ m^{-3}$. This doped semiconductor is:

Which statement is correct for a $p$-type semiconductor?

$A$ hole in a $P-$type semiconductor is

If the ratio of electron and hole currents in a semiconductor is $\frac{7}{4}$ and the ratio of drift velocities of electrons and holes is $\frac{5}{4}$, then the ratio of concentrations of electrons and holes will be