Classification of Elements Part 1

Here, (B), (C) and (D) are p-block elements of the 2 nd period.
(D) ⟶p1 configuration → B of group 13
(C) ⟶p3 configuration →N of group 15
(B) ⟶p4 configuration → O of group 16 We know, ionisation enthalpy (∆iH)∝ stability of the subshell concerned.
Therefore, half-filled subshell is more stable than partially filled.
∴∆iH order is c>b>>d
(A) is a s-block element (group 2) of 2nd period with s2-configuration → Be of group 2 [fully-filled; stable]
So, the correct order of IE, or ∆iH1 (in kJmol−1 ) of the 2 nd period elements will beThe correct matching is (A)-(ii), (B)-(iii), (C)-(iv), (D)-(i)
Note The order of IE, or ∆iH1 of 2 nd period elements is
Li<B<Be<C<O<N<F<Ne