The earlier concept of oxidation and reduction is based on the addition or removal of oxygen or hydrogen elements so, in terms of oxygen and hydrogen, oxidation is addition of oxygen to a substance and removal of hydrogen from a substance. On the other hand, reduction is addition of hydrogen to a substance and removal of oxygen from a substance. The substance which gives oxygen to another substance or removes hydrogen from another substance in an oxidation reaction is known as oxidising agent, while the substance which gives. hydrogen to another substance or removes oxygen from another substance in a reduction reaction is known are reducing agent. A redox reaction is one in which

Options

A. both the substances are reduced
B. both the substances are oxidised
C. an acid is neutralised by the base
D. one substance is oxidised while the other is reduced