An $N-$type and $P-$type silicon can be obtained by doping pure silicon with

Statement-$I$: By doping silicon semiconductor with pentavalent material,the electron density increases.
Statement-$II$: The $n$-type semiconductor has a net negative charge.
In the light of the above statements,choose the most appropriate answer from the options given below:

How is electric conduction produced in an intrinsic semiconductor?

In a $P$-type semiconductor,there is

$A$ 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 $n_i = 1.5 \times 10^{16} \, m^{-3}$)

When $Ge$ crystals are doped with phosphorus atoms,then it becomes