Engineering Questions with Answers - Multiple Choice Questions

Applied Chemistry MCQ – Estimation of Hardness – 1

1 - Question

Soaps can be defined as the soap consuming capacity of the water sample.
a) True
b) False

View Answer

Answer: a
Explanation: Soaps are defined as the soap consuming capacity of the water. Soaps are sodium salts of fatty acids like oleic acid and stearic acid.




2 - Question

The soft water contains the hardness of about ____________
a) 0-45ppm
b) 0-55ppm
c) 0-65ppm
d) 0-75ppm

View Answer

Answer: d
Explanation: The soft water contains the hardness of about 0-75ppm. The hardness of water is mainly due to the salts of calcium and magnesium.




3 - Question

The hardness of moderately hard water is about _____________
a) 75-150ppm
b) 75-120ppm
c) 75-130ppm
d) 75-100ppm

View Answer

Answer: a
Explanation: The hardness of CaCO3 of moderately hard water is about 75-150ppm. The hardness of the water can be calculated from amount of calcium and magnesium ions present in water along with bicarbonates, sulphates.




4 - Question

The very hard water has the hardness of CaCO3 is given by ___________
a) 100-200ppm
b) 100-300ppm
c) 200-300ppm
d) Above 300ppm

View Answer

Answer: c
Explanation: The very hard water has the hardness of CaCO3 is given about above 300ppm. The hard water is having the hardness of CaCO3 is given by 150-300ppm.




5 - Question

The PH value of the drinking water is about _________
a) 6.5-8.5
b) 5.5-6.5
c) 4.5-5.5
d) 3.5-4.5

View Answer

Answer: a
Explanation: The PH value of the drinking water is about 6.5 to 8.5. The odour of the drinking water is unobjectionable but the drinking water is generally having no odour.




6 - Question

The drinking water can have the magnesium limit about ____________
a) 10-150ppm
b) 20-150ppm
c) 30-150ppm
d) 40-150ppm

View Answer

Answer: c
Explanation: The drinking water can have the magnesium limit about 30-150ppm. The calcium in the drinking water can be about 75-200ppm.




7 - Question

The chloride in drinking water range can be about ___________
a) 200-600ppm
b) 300-600ppm
c) 400-600ppm
d) 500-600ppm

View Answer

Answer: a
Explanation: The chloride in drinking water range can be about 200-600ppm. The nitrate is about the range of 45ppm in drinking water.




8 - Question

The iron is about the range in drinking water is _________
a) 1-1.5ppm
b) 0.01-0.1ppm
c) 1-1.1ppm
d) 0.1-1ppm

View Answer

Answer: d
Explanation: The iron is about the range in drinking water is 0.1-1.0ppm. The magnesium is about the range of 30-150ppm in drinking water.




9 - Question

The phosphate is about the range of __________ in drinking water.
a) 5-10ppm
b) 10-15ppm
c) 15-20ppm
d) 20-25ppm

View Answer

Answer: b
Explanation: The phosphate is about the range of 10-15ppm in drinking water. The sulphate in drinking water is about 200-400ppm.




10 - Question

The organic matter in drinking water must be about _________
a) 0.2-1.0ppm
b) 1.0-2.0ppm
c) 2.0-3.0ppm
d) 3.0-4.0ppm

View Answer

Answer: a
Explanation: The organic matter in drinking water must be about 0.2-1.0ppm. The phosphate is also low that is about 10-15ppm.




11 - Question

In _____________ when the eater is heated then the soluble salts turns into insoluble ones and removed by filtration.
a) Temporary hardness
b) Permanent hardness
c) Non-carbonate
d) Non-alkaline

View Answer

Answer: a
Explanation: The hardness in the temporary hard water can be removed by heating and filtrating the insoluble salts.




12 - Question

Which of the following does not cause the permanent hardness in water?
a) Nitrates
b) Sulphates
c) Chlorides
d) Bicarbonates

View Answer

Answer: d
Explanation: The bicarbonates of the calcium and magnesium cause the temporary hardness and the sulphides, nitrates and the chlorides cause permanent hardness.




13 - Question

The total hardness can be given by _________
a) Temporary + permanent hardness
b) Temporary – permanent hardness
c) Temporary * permanent hardness
d) Temporary/permanent hardness

View Answer

Answer: a
Explanation: The sum of the temporary and permanent hardness of the water gives the total hardness of the water.




14 - Question

Which of the following process does not remove the permanent hardness of water?
a) Lime-soda
b) Ion exchange process
c) Zeolite process
d) Heating

View Answer

Answer: c
Explanation: Heating of the water removes the temporary hardness and the permanent hardness is removed by the zeolite process, lime soda process and the ion exchange method.




15 - Question

All carbonate and bicarbonates are _________
a) Alkaline
b) Acidic
c) Highly acidic
d) Neutral

View Answer

Answer: a
Explanation: All the carbonates and bicarbonates are alkaline in nature. So, the hardness due to them is called carbonate hardness or alkaline hardness.

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