In potassium ferrocyanide, there are _______ pairs of electrons in the t$$_{2g}$$ set of orbitals.

Potassium ferrocyanide is K₄[Fe(CN)₆].

Fe is in +2 oxidation state: Fe²⁺ has electron configuration [Ar]3d⁶.

CN⁻ is a strong field ligand, causing pairing (low spin complex).

In octahedral low spin d⁶: $$t_{2g}^6 e_g^0$$

The $$t_{2g}$$ set has 6 electrons arranged in 3 orbitals, meaning 3 pairs.

The number of pairs of electrons in $$t_{2g}$$ = 3.