Oxidation state is a number that is assigned to an element in a chemical combination. The number represents the number of electrons that an atom can gain, loses, or share when chemically bonding with an atom of another element. In this case the oxidation state or the oxidation number of Ca(NO3)2 is Zero, since its an electrically neutral compound. Thus the sum of oxidation number of calcium, nitrogen and oxygen is zero.
The correct awser is the D/the 4th one
