Engineering Questions with Answers - Multiple Choice Questions

Environmental Engineering MCQ’s – Types of Hardness and Method of their Removal

1 - Question

 The Total hardness of soft water as CaCO3 equivalent is __________
a) 50ppm
b) 100ppm
c) 150ppm
d) 200ppm

View Answer

Answer: a
Explanation: The Total hardness of soft water as CaCO3 equivalent is 50ppm while of hard water, it is 150-300ppm.




2 - Question

 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

View Answer

Answer: b
Explanation: When the total hardness of water is between 50 and 150ppm as CaCO3 equivalent, then the water is moderately hard.




3 - Question

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

View Answer

Answer: b
Explanation: The permanent hardness is due to the presence of sulfates, chlorides and nitrates of calcium and magnesium in water.




4 - Question

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

View Answer

Answer: c
Explanation: The temporary hardness is due to the presence of carbonates and bicarbonates of calcium and magnesium in water.




5 - Question

 Which of the following causes the temporary hardness?
a) CaSO4
b) MgSO4
c) MgCl2
d) Ca (HCO32

View Answer

Answer: d
Explanation: As the temporary hardness is caused due to the presence of carbonate and bicarbonates, therefore Ca (HCO3) 2 cause temporary hardness.




6 - Question

The permanent hardness is also known as __________
a) Pseudo hardness
b) Non carbonate hardness
c) Carbonate hardness
d) Brinell hardness

View Answer

Answer: b
Explanation: The permanent hardness is also known as non carbonate hardness whereas temporary hardness is also known as carbonate hardness.




7 - Question

Which of the following is not used for removing the permanent hardness?
a) Lime soda process
b) Zeolite process
c) Demineralization
d) Adding lime

View Answer

Answer: d
Explanation: Adding lime is a method that is used to remove temporary hardness and it cannot remove the permanent hardness.




8 - Question

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

View Answer

Answer: c
Explanation: 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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