This set of Applied Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Estimation of Hardness – 1”.
1. Soaps can be defined as the soap consuming capacity of the water sample.
a) True
b) False
View Answer
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. The soft water contains the hardness of about ____________
a) 0-45ppm
b) 0-55ppm
c) 0-65ppm
d) 0-75ppm
View Answer
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. The hardness of moderately hard water is about _____________
a) 75-150ppm
b) 75-120ppm
c) 75-130ppm
d) 75-100ppm
View Answer
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. 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
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. 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
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. The drinking water can have the magnesium limit about ____________
a) 10-150ppm
b) 20-150ppm
c) 30-150ppm
d) 40-150ppm
View Answer
Explanation: The drinking water can have the magnesium limit about 30-150ppm. The calcium in the drinking water can be about 75-200ppm.
7. The chloride in drinking water range can be about ___________
a) 200-600ppm
b) 300-600ppm
c) 400-600ppm
d) 500-600ppm
View Answer
Explanation: The chloride in drinking water range can be about 200-600ppm. The nitrate is about the range of 45ppm in drinking water.
8. 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
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. The phosphate is about the range of __________ in drinking water.
a) 5-10ppm
b) 10-15ppm
c) 15-20ppm
d) 20-25ppm
View Answer
Explanation: The phosphate is about the range of 10-15ppm in drinking water. The sulphate in drinking water is about 200-400ppm.
10. 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
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. 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
Explanation: The hardness in the temporary hard water can be removed by heating and filtrating the insoluble salts.
12. Which of the following does not cause the permanent hardness in water?
a) Nitrates
b) Sulphates
c) Chlorides
d) Bicarbonates
View Answer
Explanation: The bicarbonates of the calcium and magnesium cause the temporary hardness and the sulphides, nitrates and the chlorides cause permanent hardness.
13. 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
Explanation: The sum of the temporary and permanent hardness of the water gives the total hardness of the water.
14. 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
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. All carbonate and bicarbonates are _________
a) Alkaline
b) Acidic
c) Highly acidic
d) Neutral
View Answer
Explanation: All the carbonates and bicarbonates are alkaline in nature. So, the hardness due to them is called carbonate hardness or alkaline hardness.
Sanfoundry Global Education & Learning Series – Applied Chemistry.
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