$A$ $P-$ type semiconductor can be obtained by adding

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

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

Assertion: The number of electrons in a $p-$type silicon semiconductor is less than the number of electrons in a pure silicon semiconductor at room temperature.
Reason: It is due to the law of mass action.

The contribution in the total current flowing through a semiconductor due to electrons and holes are $\frac{3}{4}$ and $\frac{1}{4}$ respectively. If the drift velocity of electrons is $\frac{5}{2}$ times that of holes at this temperature,then the ratio of concentration of electrons and holes is

In $n$-type semiconductor,electrons are majority charge carriers,but it does not show any negative charge. The reason is: