$2\mathrm{.}13$ Without consulting Figure $2\mathrm{.}8$ or Table $2\mathrm{.}2,$ determine whether each of the electron configurations given below is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices.

$($a$)1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{7}4s^2$

$($b$)1s^{2}2s^{2}2p^{6}3s^{2}3p^6$

$($c$)1s^{2}2s^{2}2p^5$

$($d$)1s^{2}2s^{2}2p^{6}3s^2$

$($e$)1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{2}4s^2$

$($f$)1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^1$