The sum of `IE_(1)` and `IE_(2)` and those of `IE_(3)` and `IE_(4)` in `(kJ mol^(-1))` of `Ni` and `Pt` are :
`{:(,(IE_(1)+IE_(2)),(IE_(3)+IE_(4)),"Total",),(Ni,2.5 xx 10^(3),8.8 xx 10^(3),11.3 xx 10^(3),),(Pt,2.7 xx 10^(3),6.7 xx 10^(3),9.4 xx 10^(3),):}`
a. What is the most common oxidation state (O.S.) of `Ni` and `Pt`.
b. Name of the metal (`Ni`or `Pt`) which can more easily form compounds in its `+4` O.S.

Explanation

(a) The most common oxidation state of Ni is +2 and of Pt is +4 because these have lower ionization enthalpies.
(b) Platinum because the sum of first four ionization enthalpies for Pt is lower than that for Ni.