Hint :Oxidation state: It is the number of electrons which are lost or gained by a neutral atom while a chemical bond is formed. It can also be termed as oxidation number. If the electrons are lost by a neutral atom, then the oxidation number will have a positive value whereas if a neutral atom gains an electron, then it will have a negative oxidation state.
Complete Step By Step Answer: Some major rules to find the oxidation state of an element in a compound are as follows: A free element i.e., an element which is not connected to any other atom or is chemically bonded to itself will have zero oxidation state. For the monatomic ion, its oxidation state will be equal to the value of the charge present on the ion. The oxidation state of oxygen atoms is $ ( - 2) $ but there is an exceptional case of peroxides that is in peroxides the oxidation number for oxygen atoms is $ ( - 1) $ . In a molecule, the sum of oxidation number of each element present will be equal to overall charge on the molecule (it will be equal to zero for a neutral molecule). Generally, the oxidation number for hydrogen atoms is $ ( + 1) $ but in case of compounds which have less electronegative elements than hydrogen, for that case oxidation number for hydrogen atom is $ ( - 1) $ .
Note : When there is an increase in the oxidation state of an atom then the process is known as oxidation and the atom which is oxidized is termed as reducing agent. When there is a decrease in the oxidation state of an atom then the process is known as reduction and the atom which is reduced is termed as oxidizing agent.