Out of the following impurities, which impurity is not a trivalent?

If $n_{e}$ and $n_{h}$ are the number of electrons and number of holes respectively in a semiconductor heavily doped with phosphorus,then:

$A$ 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 centimetre will be:

If the number of holes and electrons are represented by $n_h$ and $n_e$ respectively,then which of the following is correct for an intrinsic semiconductor?

The impurity atom added to germanium to make it $N-$type semiconductor is

The length of a germanium rod is $0.928 \ cm$ and its area of cross-section is $1 \ mm^2$. If for germanium $n_i = 2.5 \times 10^{19} \ m^{-3}$,$\mu_h = 0.15 \ m^2 V^{-1} s^{-1}$,and $\mu_e = 0.35 \ m^2 V^{-1} s^{-1}$,then the resistivity is: