Chlorine is prepared on a large scale by the

• A electrolysis of concentrated sodium chloride solution
• B action of manganese (IV) oxide on hot concentrated hydrochloric acid
• C action of concentrated tetraoxosulphate (IV) acid on sodium chloride
• D oxidation of concentrated hydrochloric acid with potassium tetraxosulphate (VII)
• E action of dilute mineral acids on bleaching powder