250+ TOP MCQs on Types of Hardness and Method of their Removal and Answers

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Environmental Engineering Questions for Freshers on “Types of Hardness and Method of their Removal”.

1. The Total hardness of soft water as CaCO3 equivalent is __________
a) 50ppm
b) 100ppm
c) 150ppm
d) 200ppm
Answer: a
Clarification: The Total hardness of soft water as CaCO3 equivalent is 50ppm while of hard water, it is 150-300ppm.

2. The total hardness of water is 100ppm as CaCO3 equivalent. What is the type of water?
a) Soft
b) Moderately hard
c) Hard
d) Very hard
Answer: b
Clarification: When the total hardness of water is between 50 and 150ppm as CaCO3 equivalent, then the water is moderately hard.

3. The permanent hardness in water is due to the presence of __________
a) Sulfates, Chlorides
b) Sulfates, chlorides, nitrates
c) Carbonates and bicarbonates
d) Sulfates and carbonates
Answer: b
Clarification: The permanent hardness is due to the presence of sulfates, chlorides and nitrates of calcium and magnesium in water.

4. The temporary hardness in water is due to the presence of __________
a) Sulfates, Chlorides
b) Sulfates, Chlorides, nitrates
c) Carbonates and bicarbonates
d) Sulfates and carbonates
Answer: c
Clarification: The temporary hardness is due to the presence of carbonates and bicarbonates of calcium and magnesium in water.

5. Which of the following causes the temporary hardness?
a) CaSO4
b) MgSO4
c) MgCl2
d) Ca (HCO3) 2
Answer: d
Clarification: As the temporary hardness is caused due to the presence of carbonate and bicarbonates, therefore Ca (HCO3) 2 cause temporary hardness.

6. The permanent hardness is also known as __________
a) Pseudo hardness
b) Non carbonate hardness
c) Carbonate hardness
d) Brinell hardness
Answer: b
Clarification: The permanent hardness is also known as non carbonate hardness whereas temporary hardness is also known as carbonate hardness.

7. Which of the following is not used for removing the permanent hardness?
a) Lime soda process
b) Zeolite process
c) Demineralization
d) Adding lime
Answer: d
Clarification: Adding lime is a method that is used to remove temporary hardness and it cannot remove the permanent hardness.

8. Which of the following statement is wrong regarding hard water?
a) It causes more consumption of soap in laundry work
b) It causes difficulties in the manufacturing process
c) It increases the taste of food
d) It causes the formation of scales on the boilers
Answer: c
Clarification: Hard water makes the food tasteless, tough and rubbery. So, the process of softening is done to improve the cooking of food.

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