Missing question:
(a) 1s2 2s2 2p6 3s1
(b) 1s2 2s2 2p6 3s2
(c) 1s2 2s2 2p6 3s2 3p1
(d) 1s2 2s2 2p6 3s2 3p4
(e) 1s2 2s2 2p6 3s2 3p5
Answer is: a) 1s²2s²2p⁶3s¹ (sodium).
Sodium have the largest second ionization energy, because when he lost one electron(first ionization energy), he have stable electron configuration of noble gas neon (1s²2s²2p⁶), so sodium do not need to lost second electron, because he will have unstable electron configuration.
Potassium (K), Sodium(Na), Iron(Fe), Copper(Cu), Silver(Ag), Tin(Sn), Antimony(Sb), Tungsten(W), Gold(Au), Mercury(Hg), Lead(Pb)
X has valency 3 and oxide ion has valency 2
So, the formula of oxide will be X
2
O
3
