Question

what is redox reaction? identify the substance oxidised and the substance reduce in the following reaction.
(a) pb3O4 + BHCl ------> 3pbCl2 + Cl2 + 4H2O
@CuO + H2 -------> Cu + H2O

Answer 1

redox is a chemical reaction in which Oxidation state is changed

Answer 2

REDOX REACTION is a type of chemical reaction which involves transfer of electron between 2 species. it's also known as oxidation reduction reaction.

OR

REDOX REACTION is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron.

Hope this helps you :)