Hardness of Water Multiple Choice Questions and Answers

1. A water sample found to possess 16.2 mg/L of Ca(HCO₃)₂. Its hardness in terms of CaCO₃ equivalents is

1. 100
2. 10
3. 16.2
4. 1000

2. Biological oxidation processes usually referred as biological treatment, are the most common form of

1. Primary treatment
2. secondary treatment
3. Tertiary treatment
4. all of the above

3. Blow – down operation cause the removal of

1. Scales
2. sludges
3. acidity
4. sodium chloride

4. Boiler corrosion caused by using high alkaline water in a boiler is called

1. Corrosion
2. boiler corrosion
3. caustic embrittlement
4. erosion

5. Brackish water mainly contains

1. Calcium salts
2. Magnesium salts
3. Turbidity
4. sodium chloride

6. Calgon is the trade name given to

1. Sodium silicate
2. Sodium hexa meta phosphate
3. Sodium meta phosphate
4. Calcium phosphate

7. Calgon is used for the removal of

1. Sodium carbonate
2. permanent hardness of water
3. Hardness of water
4. none of these

8. Caustic embrittlement can be avoided by using

1. Sodium phosphate
2. hydrogen
3. ammonium hydroxide
4. sodium sulphate

9. Caustic embrittlement is a type of

1. Boiler corrosion
2. conditioning
3. scale formation
4. sludge formation.

10. Disinfection by ozone is due to liberation of

1. Oxygen
2. nascent Oxygen
3. Molecular Oxygen
4. oxide