Substances that cause a reaction to occur or proceed at a different rate without the reaction itself being affected are called - (1) Catalysts (2) Hydrocarbons (3) Oxidising agents (4) Substitutes
(1) Catalysts Explanation: Catalysts are substances that cause a reaction to occur or proceed at a different rate without the reaction itself being affected. Eg: hydrogenation of vegetable oils using a nickel catalyst.