Indium impurity in germanium makes

In an $n$-type silicon,which of the following statements is true?

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

An $n$-type and $p$-type semiconductor can be obtained by respectively doping pure silicon with

The density of an electron-hole pair in a pure germanium is $3 \times 10^{16} \ m^{-3}$ at room temperature. On doping with aluminium,the hole density increases to $4.5 \times 10^{22} \ m^{-3}$. Now,the electron density (in $m^{-3}$) in doped germanium is:

What is the number density of donor atoms which must be added to a pure germanium semiconductor to make an $n$-type semiconductor of conductivity $6.4 \ \Omega^{-1} \ cm^{-1}$? The mobility of electrons in $n$-type germanium is $4 \times 10^3 \ cm^2 \ V^{-1} \ s^{-1}$. Neglect the contribution of holes to conductivity.