a. The hardness of water is mainly due to the presence of (i) Carbonate, bicarbonate, chlorides and sulfates of calcium and magnesium (ii) Carbonate, bicarbonates of calcium and magnesium (iii) Chlorides and sulfates of calcium and magnesium (iv) Nitrate and sulfates of calcium and magnesium b. The hard water (i) is not tasty (ii) is softened water (iii) consumes more soap for cleaning purposes (iv) consumes more chlorine as disinfectant c. The measurement of conductivity may lead to the estimation of (i) Total solids (ii) Total dissolved solids (iii) Suspended solids (iv) Colloidal solids d. Most common ion in the water is (i) Fluoride (ii) Nitrate (iii) Chloride (iv) Sulfate e. The factor of converting the concentration of CO32 - from "as ion" to "as CaCO3 " is (i) 2.18 (ii) 0.82 (iii) 1.04 (iv) 1.67 f. Which of the following is used as a chemical coagulant? (i) calcium chloride (ii) alum (iii) lime (iv) soda ash g. In determining the proper dosage of alum, the most useful test is the test: pH (i) hardenss (ii) jar (iii) carbonate (iv) pH h. Carbon dioxide is used in water treatment to do what? (i) disinfect (ii) raise pH (iii) lower pH (iv) stabilize ammonia compounds i. A method used to soften water is (i) aeration (ii) sedimentation (iii) ion exchange (iv) adsorpti