Q$\mathrm{.}2($a$)$ If the electron concentration is $2\mathrm{.}51012$ cm$-3$ in a semiconductor Ge sample, determine the type $($n or p$)$ of the Ge sample at $250$ K and $300$ K$,$ respectively. Briefly explain your answer. $(6$ marks$)($b$)$ Write down the equations for the charge neutrality condition for the Ge sample in part $($a$)$ at $250$ K and $300$ K$,$ respectively. $(4$ marks$)$