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

Which statement is correct for a $p$-type semiconductor?

When phosphorus and antimony are mixed in germanium,then:

In a sample of pure silicon, $10^{13} \text{ atoms/cm}^3$ of phosphorus is added. If all donor atoms are active and the electron mobility is $1200 \text{ cm}^2/\text{V}\cdot\text{s}$, what will be the resistivity at $20^\circ\text{C}$ in $\Omega\cdot\text{cm}$?

The net charge on an $N-$type semiconductor is

Write four points in distinguishing between $p$-type semiconductor and $n$-type semiconductor.