Which one of the following statements is false?

Silicon is a semiconductor. If a small amount of $As$ is added to it,then its electrical conductivity . . . . . . .

Pure silicon at $300 \ K$ has equal electron and hole concentration of $1.5 \times 10^{16} \ m^{-3}$. If the hole concentration increases to $3 \times 10^{22} \ m^{-3}$,then the electron concentration in the silicon is

$P-$type semiconductor is formed when:

Suppose an $n$-type wafer is created by doping $Si$ crystal having $5 \times 10^{28} \text{ atoms/m}^3$ with $1 \text{ ppm}$ concentration of $As$. On the surface,$200 \text{ ppm}$ Boron is added to create a $p$-region in this wafer. Considering $n_i = 1.5 \times 10^{16} \text{ m}^{-3}$,$(i)$ Calculate the densities of the charge carriers in the $n$ and $p$ regions. $(ii)$ Comment on which charge carriers would contribute largely to the reverse saturation current when the diode is reverse biased.

Mobility of electrons in a semiconductor is defined as the ratio of their drift velocity to the applied electric field. If,for an $n$-type semiconductor,the density of electrons is $10^{19} \ m^{-3}$ and their mobility is $1.6 \ m^2/(V \cdot s)$,then the resistivity of the semiconductor (since it is an $n$-type semiconductor,the contribution of holes is ignored) is close to ................ $\Omega \cdot m$.