Chemistry - PERIODIC TABLE Question with Solution | TestHub

For pair (IV) Sn and Pb, due to poor shielding by d and f electrons (inert pair effect), the ionization energy (IE) of Pb is slightly higher than Sn, so Sn < Pb (R).

Therefore, factor (2) Charge on nucleus alone cannot explain pair (IV) with $x>y$ (P). Hence, the combination (2), (IV), (P) is incorrect.

Other combinations are correct:

(1), (II), (P): Na > K due to the larger size of K.

(3), (IV), (R): poor shielding effect.

(2), (III), (R): S < Cl due to the higher nuclear charge of Cl.