The charge carriers in a $p$-type semiconductor are

In an intrinsic semiconductor,the density of conduction electrons is $7.07 \times 10^{15} \, m^{-3}$. When it is doped with indium,the density of holes becomes $5 \times 10^{22} \, m^{-3}$. Find the density of conduction electrons in the doped semiconductor.

Which of the following statements is not true?

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

Indium impurity is added to a sample of $Si$ to prepare a $p$-type semiconductor. In this semiconductor,one atom of indium is added per $5 \times 10^7$ atoms of $Si$. The atomic density of the $Si$ sample is $5 \times 10^{28} \text{ atoms/m}^3$. How many acceptor atoms will be present in a $1 \text{ cm}^3$ cube of silicon?