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

In an intrinsic semiconductor,the density of conduction electrons is $7.07 \times 10^{15} \, m^{-3}$. When it is doped with indium,the density of holes becomes $5 \times 10^{22} \, m^{-3}$. Find the density of conduction electrons in the doped semiconductor.

Pure $Si$ at $500\, K$ has equal number of electron $(n_e)$ and hole $(n_h)$ concentrations of $1.5 \times 10^{16} \, m^{-3}$. Doping by indium increases $n_h$ to $4.5 \times 10^{22} \, m^{-3}$. The doped semiconductor is of:

$A$ pure $Si$ crystal has $5 \times 10^{28}$ atoms $m^{-3}$. It is doped with $1 \, ppm$ concentration of pentavalent $As$. The number of holes is (Take $n_i = 1.5 \times 10^{16} \, m^{-3}$)

Doping of a semiconductor (with small impurity atoms) generally changes the resistivity as follows.

In $N$-type semiconductors,the majority charge carriers are