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

Which of the following statements is incorrect?

$A$ pure $Si$ crystal has $4 \times 10^{28}$ atoms per $m^3$. It is doped with $1 \text{ ppm}$ concentration of antimony. The number of free electrons available will be

In a junction diode,the holes are due to

$A$ 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 $0.53 \mathring{A}$).

What will be the conductivity of a pure silicon crystal at $300 \ K$? Given that the intrinsic carrier concentration is $1.072 \times 10^{10} \ cm^{-3}$ and at this temperature,the electron mobility $\mu_n = 1350 \ cm^2 / (V \cdot s)$ and hole mobility $\mu_p = 480 \ cm^2 / (V \cdot s)$.