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

Which of the following dopants is used in germanium to form an $n$-type semiconductor?

In an $n$-type semiconductor:

$A$ positive hole in a semiconductor is

Which of the following statements is incorrect?