c
(c)Number density of atoms in silicon specimen \(= 5 × 10^{28} \,\,atom/m^{3} = 5 × 10^{22}\,\, atom/cm^{3}\)
Since one atom of indium is doped in \(5 × 10^{7}\) Si atom. So number of indium atoms doped per \(cm^3\) of silicon.\(n = \frac{{5 \times {{10}^{22}}}}{{5 \times {{10}^7}}} = 1 \times {10^{15}}\,atom/c{m^3}\)