(a) defi ne oxidation and reduction (redox) in terms of oxygenhydrogen gainlossbr (b) defi ne redox in terms of electron transferbr (c) identify redox reactions in terms of oxygenhydrogen, andor electron, gainlossbr (d) describe the use of aqueous potassium iodide in testing for oxidising agents and acidifi ed potassiumbr manganate(VII) in testing for reducing agents from the resulting colour changes