Write the rules for assigning oxidation number.

Explanation

(1) All atoms in the elemental or molecules state have zero oxidation state.
(2) Elements of group I and II in the periodic table always have +1 and +2 oxidation states respectively
(3) Hydrogen has +1 oxidation state in all its compounds except metal hydrides, where it is -1.
(4) Oxygen has been assigned as oxidation number of -2 in all its compounds except perocides and oxygen fluoride. In peroxide it is -1 and in oxygen fluoride it is +2.
(5) Halogens generally have -1 oxidation state Except fluorine. other halogens may have positive oxidation states in their oxides and inter halogen compounds (Fluorine always has -1 state).
(6) The algebraic sum of the oxidation number of all the elements in a compound is zero and that in an ion is equal to the net charge on the ion.