"Oxidation number denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron pair in a covalent bond belongs entirely to a more electronegative element."
Oxidation state exhibited by Boron
Boron is an element of group 13.
The electronic configuration of boron is .
Boron is less electronegative than even hydrogen.
Boron exhibits oxidation state.
The atoms of these elements have 3 valence electrons, therefore all these elements show maximum of + 3 oxidation state.