<prompt> Softening is recommended when hardeness of water is more than?50 mglitre75 mglitre100 mglitre150 mglitre  <response>: ANSWER: D 150 mglitreREF: Park 20th ed p. 636Indirect repeat from primary DNB CET December 2011Drinking water should be moderately hard. Softening of drinking water Is recommended when the hardness exceeds 3 mEqL 150 mglitreClassificationLevel of hardness mEqLSoft water 1 50 mg1Moderately hard1-3 50-150 mgdHard water3-6 150-300 mg1Very hard water6 300 mg1 