Which of the following statements is incorrect?

In a pure silicon $(n_i = 10^{16}/m^3)$ crystal at $300\, K$,$10^{21}$ atoms of phosphorus are added per cubic meter. The new hole concentration will be

The semiconductors are generally

In an intrinsic semiconductor,the energy gap $E_{g}$ is $1.2 \; eV$. Its hole mobility is much smaller than electron mobility and independent of temperature. What is the ratio between conductivity at $600 \; K$ and that at $300 \; K$? Assume that the temperature dependence of intrinsic carrier concentration $n_{i}$ is given by $n_{i} = n_{0} \exp \left(-\frac{E_{g}}{2 k_{B} T}\right)$,where $n_{0}$ is a constant.

Mobilities of electrons and holes in a sample of intrinsic $Ge$ at room temperature are $0.35 \, m^2/V-s$ and $0.18 \, m^2/V-s$ respectively. If the electron and hole densities are each equal to $2.5 \times 10^{19} \, /m^3$,the $Ge$ conductivity will be.....$S/m$ (in $.12$)

Which of the following statements is not true?