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

If $n_e$ and $v_d$ are the number of electrons and drift velocity in a semiconductor, respectively, what happens when the temperature is increased?

Explain the concept of the hole in the semiconductor.

When a small amount of impurity atoms are added to a semiconductor,then generally its resistivity

In an $n$-type semiconductor,the Fermi energy level lies

$A$ pure semiconductor crystal has $8 \times 10^{28} \text{ atoms/m}^3$. It is doped with a $2 \text{ ppm}$ concentration of pentavalent atoms. The number of holes formed in the semiconductor crystal is (Intrinsic carrier concentration,$n_i = 1 \times 10^{16} \text{ m}^{-3}$).