Complete removal of both the axial ligands (along the z-axis) from an octahedral complex leads to which of the following splitting patterns? (relative orbital energies not on scale).

The increasing order of the pK_b of the following compound is :

The group number, number of valence electrons, and valency of an element with atomic number 15, respectively, are:

The complex ion that will lose its crystal field stabilization energy upon oxidation of its metal to +3 state is :