Hardness of Water Multiple Choice Questions and Answers for Practice

16. Hardness of water is expressed in equivalents of

1. CaCO₃
2. MgCO₃
3. Ca(HCO₃)₂
4. Mg(HCO³)²

17. Hardness of water is measured in

1. Degree Clarke
2. ppm
3. degree French
4. mg /L

18. Liquid chlorine is a most effective

1. Disinfectant
2. coagulant
3. floculant
4. sterilizing agent

19. One of the following chemical acts as both coagulant and softening agent

1. Lime
2. soda
3. soda
4. sodium aluminate

20. One of the following is an example for cation exchanging resin

1. Copolymer of phenol formaldehyde – amine formaldehyde
2. Copolymer of styrene – divinyl benzene
3. Copolymer of phenol formaldehyde and styrene
4. Copolymer of amine formaldehyde and divinely benzene

21. One part of CaCO₃ equivalent hardness per 10⁵ parts of water is called

1. Degree Clarke
2. ppm
3. degree French
4. mg /L

22. Permanent hardness in water is caused by the presence of

1. Bicarbonates of calcium and magnesium
2. Carbonates of sodium and potassium
3. Chlorides of sulfates and calcium and magnesium
4. Phosphates of sodium and potassium

23. Solubility of calcium sulphate in water is

1. Increase with rise of temperature
2. Decreases with rise of temperature
3. Remains unaltered with rise of temperature
4. Does not adopt any definite pattern with rise of temperature.

24. Temporary hardness in water is removed by

1. Filtration
2. Sedimentation
3. Boiling
4. coagulation.

25. Temporary hardness of water is caused by the presence of

1. Chlorides of calcium and magnesium
2. Sulfates of calcium and magnesium
3. Bicarbonates of calcium and magnesium
4. Carbonates of calcium and magnesium.

26. The common methods used for disinfection in waste water treatment plants are

1. Chlorination
2. UV light
3. Both a & b
4. Phenolic solvent

27. The external treatment of boiler feed water is done by

1. Lime – soda process
2. sodium sulphate treatment
3. Calgon process
4. sodium aluminate treatment.

28. The formula of chloramine is

1. ClNH₂
2. NHCl₂
3. NCl₃
4. NH₂Cl₂

29. The hardness of water in CaCO₃ equivalents containing MgSO₄ (Mol. Wt = 120) with concentration of 12 mg/ L is

1. 100 mg/L
2. 10 mg/L
3. 5 mg/L
4. 1 mg/L

30. The hardness of water sample is 10 ppm, which can be expressed as.............degree Clarke.

1. 0.3
2. 0.4
3. 0.5
4. 0.7