1The process that removes suspended particles with alum is:AAerationBDisinfectionCSofteningDCoagulation and flocculationView AnswerDiscussWorkspaceReportSaveEasy
2The acceptable pH range of drinking water (BIS) is:A4–5B6.5–8.5C1–3D9–11View AnswerDiscussWorkspaceReportSaveEasy
3Hardness of water is caused mainly by:AIron onlyBCalcium and magnesium saltsCDissolved oxygenDSodium chlorideView AnswerDiscussWorkspaceReportSaveEasy
4Break-point chlorination ensures:AA free chlorine residual after demand is satisfiedBNo chlorine remainsCRemoval of turbidityDMaximum hardnessView AnswerDiscussWorkspaceReportSaveEasy
5Slow sand filters remove impurities mainly by:AHigh pressureBBoilingCChemical reactionDBiological action in the top layer (schmutzdecke)View AnswerDiscussWorkspaceReportSaveEasy