Residual chlorine in drinking water should be-: (A) 0.5 mg /L, (B) 0.7 mg/L, (C) 1 mg/L, (D) 2 mg/L
Answer is A. Ans. is 'a' i.e., 0.5 mg /L Water typeRecommendedResidual chlorine levelContact periodDrinking water> 0.5 mg per litre (ppm)1 hourWater bodies, post disaster> 0.7 mg per litre (ppm)1 hourSwimming pool sanitation>1.0 mg per litre (ppm)1 hour