Problem

The key insight here is recognizing that variable oxidation states in transition metals arise from the availability of both $d$ and $s$ electrons for bonding. Since $3d$ electrons are only slightly higher in energy than $4s$ electrons, transition metals can readily lose different numbers of them, creating multiple stable oxidation states. When two states differ by exactly 2 units, you're looking at the loss (or gain) of two electrons—typically from the $d$ orbitals—which tells you something specific about the element's electron configuration and which electrons are being removed.

The key insight here is recognizing that variable oxidation states in transition metals arise from the availability of both $d$ and $s$ electrons for bonding. Since $3d$ electrons are only slightly higher in energy than $4s$ electrons, transition metals can readily lose different numbers of them, creating multiple stable oxidation states. When two states differ by exactly 2 units, you're looking at the loss (or gain) of two electrons—typically from the $d$ orbitals—which tells you something specific about the element's electron configuration and which electrons are being removed.