In an intrinsic semiconductor at room temperature,the number of electrons and holes are

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

$A$ donor atom in a semiconductor has a loosely bound electron. The orbit of this electron is considerably affected by the semiconductor material but behaves in many ways like an electron orbiting a hydrogen nucleus. Given that the electron has an effective mass of $0.07 \, m_e$,where $m_e$ is the mass of the free electron,and the space in which it moves has a permittivity of $13 \, \varepsilon_0$,then the radius of the electron's lowermost energy orbit will be close to ................. $\mathring{A}$ (take the Bohr radius of the hydrogen atom as $0.53 \mathring{A}$).

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

Pure $Si$ at $500\, K$ has equal number of electron $(n_e)$ and hole $(n_h)$ concentrations of $1.5 \times 10^{16}\, m^{-3}$. Doping by indium increases $n_h$ to $4.5 \times 10^{22}\, m^{-3}$. The doped semiconductor is of

In an $n$-type semiconductor, the Fermi energy level lies