The number densities of electrons and holes in pure silicon at 273 K are equal and their values are $1.5 \times 10^{16} m^{-3}$. On doping, the hole density increases to $4.5 \times 10^{27} m^{-3}$. The electron density in the doped silicon will be:

$5 \times 10^4 m^{-3}$

The correct answer is Option (1) → $5 \times 10^4 m^{-3}$