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

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

When an impurity is doped into an intrinsic semiconductor,the conductivity of the semiconductor

Which of the statements given is true for a $p$-type semiconductor?

Which of the following statements is not true?

The length of a germanium rod is $0.928 \ cm$ and its area of cross-section is $1 \ mm^2$. If for germanium $n_i = 2.5 \times 10^{19} \ m^{-3}$,$\mu_h = 0.15 \ m^2 V^{-1} s^{-1}$,and $\mu_e = 0.35 \ m^2 V^{-1} s^{-1}$,then the resistivity is: