What is the degeneracy of the t2g orbital set?

The t2g orbital set in the context of crystal field theory pertains specifically to the arrangement of d orbitals in transition metal complexes, particularly under an octahedral ligand field. In an octahedral environment, the five d orbitals split into two groups: the lower-energy t2g set and the higher-energy eg set.

The t2g set consists of three orbitals: dxy, dxz, and dyz. Each of these orbitals can hold a maximum of two electrons, but their degeneracy pertains to the number of orbitals present in that set. Since there are three unique t2g orbitals, the degeneracy of this set is defined as three.

This means that there are three different spatial orientations in which electrons can occupy within this energy level, contributing to the total number of possible electronic configurations within a transition metal complex. Therefore, the correct answer reflects the count of these orbitals in the t2g set, which is indeed three.