Answer : The incorrect statements are:
(A) When two nonmetals react, the compound formed is ionic.
(B) Two nonmetals can undergo an oxidation-reduction reaction.
Explanation :
Covalent compound : It is defined as the compound which is formed by the sharing of electrons between the atoms forming a compound.
The covalent compound are usually formed when two non-metals react.
The two nonmetals can not undergo an oxidation-reduction reaction.
Ionic compound : It is defined as the compound which is formed when electron gets transferred from one atom to another atom.
Ionic compound are usually formed when a metal reacts with a non-metal.
The metal-nonmetal reaction can always be assumed to be an oxidation-reduction reaction.
For example :
In this reaction, sodium shows oxidation because the oxidation state changes from (0) to (+1) and and chlorine shows reduction because the oxidation state changes from (0) to (-1).
Hence, the incorrect statements are, (A) and (B)