Respuesta :
D) When the cation is a transition metal.
For example, FeCl2 - iron (II) chloride vs FeCl3 - iron(III) chloride.
Answer is: D) when the cation is a transition metal.
The Roman numeral shows the charge and the oxidation state of the transition metal ion.
For example, cobalt can form two chlorides, with charge of 2+ (cobalt(II) chloride - CoCl₂) and with charge 3+ (cobalt(III) chloride - CoCl₃).
Transition metals are elements in the d-block of the periodic table.