A sodium atom has an electron configuration of 1s^2 2s^2 2p^6 3s^1. If the sodium atom becomes ionized, its new electron configuration will be the same as which element?

If the sodium is ionised, the outer $3 {s}^{1}$ electron is lost, so the configuration becomes
$1 {s}^{2} 2 {s}^{2} 2 {p}^{6}$,
which is the same as neon, $N e$.