<prompt> What is the principle of the given test for Urine reducing substance?Cu2 ions are reduced to Cu ions by enediolsCu ions are oxidised to Cu2 ions by enediolsFe2 ions are reduced to Fe ions by enediolsFe ions re oxidised to Fe2 ions by enediols  <response>: Ans. A. Cu2 ions are reduced to Cu ions by enediols This test is Benedicts test. The principle of the test isCu2ions present in Copper sulphate is reduced to Cuprous hydroxide and later to Cuprous oxide by enediols formed from reducing sugar 