i. Oxidation: The reaction in which substance gains oxygen or loses hydrogen is called as oxidation reaction.
eg. a. When copper powder is heated in air, it reacts with oxygen to form copper (II) oxide. In this reaction, copper gets oxidised.
b. When magnesium ribbon is burnt in air, it reacts with oxygen to form magnesium oxide. In this reaction, magnesium gets oxidised.
ii. Reduction reaction: The reaction in which substance gains hydrogen or loses oxygen is called as reduction reaction.
eg.
a. Nitrogen gas reacts with hydrogen gas in presence of a catalyst at high temperature and pressure to form ammonia gas
b. When mercuric oxide is heated, it gets reduced to metallic mercury.
