The extra stability of half-filled subshell is due to :

(A) Symmetrical distribution of electrons

(B) Smaller coulombic repulsion energy

(C) The presence of electrons with the same spin in non-degenerate orbitals

(D) Larger exchange energy

(E) Relatively smaller shielding of electrons by one another

Indentify the correct statements :

'X' is the number of acidic oxides among VO₂, V₂O₃, CrO₃, V₂O₅ and Mn₂O₇. The primary valency of cobalt in
[Co(H₂NCH₂CH₂NH₂)₃]₂(SO₄)₃ is Y. The value of X + Y is _________.

The correct statement amongst the following is :