Water Hardness MCQs

1. __________ is the end point of the titration in the soap titration method.

(A) Formation of bicarbonates

(B) Formation of salts

(C) Formation of carbonates

(D) Formation of lather

2. All the hardness causing ions can be precipitated into their respective _____ by the sodium soap.

(A) Carbonates

(B) Bicarbonates

(C) Stereates

(D) Chlorides

3. _________ is the water that forms lather directly with the soap.

(A) Hard water

(B) Very hard water

(C) Partially hard water

(D) Soft water

4. By titrating the fixed volume of water against the standard __________ solution we can determine the total hardness of the water.

(A) Alcoholic soap

(B) Alkaline soap

(C) Acidic soap

(D) Soap

5. __________ is the indicator used in the EDTA method.

(A) Benzene

(B) Phenolphthalein

(C) Ethylene diamine

(D) Eriochrome Black T

6. ___________ is the hardness a soft water contains.

(A) 0-75 ppm

(B) 0-55 ppm

(C) 0-65 ppm

(D) 0-45 ppm

7. ________ is also called EDTA method.

(A) Complexometric titration

(B) Complex titration

(C) Complement titration

(D) Complexion titration

8. By the ___ types estimation of the hardness of water can be determined.

(A) 2

(B) 3

(C) 4

(D) 5

9. To form ________ with metal ions EDTA has the ability.

(A) Salts

(B) Unstable complexes

(C) Stable complexes

(D) Acids

10. The metal-dye complex has the _______ color at pH 10.

(A) Pink

(B) Blue

(C) Green

(D) Wine red

11. ________ grams of EDTA is dissolved in one litre of water to prepare EDTA solution.

(A) 1

(B) 2

(C) 3

(D) 4

12. The standard hard water is prepared to ensure that each mL must contain _______ mg of CaCO₃.

(A) 1

(B) 2

(C) 3

(D) 4

13. The moderately hard water contains the hardness of ____________.

(A) 75-100 ppm

(B) 75-120 ppm

(C) 75-130 ppm

(D) 75-150 ppm

14. Dye and dye-metal complex have the __________ colour.

(A) Same

(B) Different

(C) Same in only some cases

(D) Cannot be known

15. The formula of total hardness can be given by ________.

(A) Temporary + permanent hardness

(B) Temporary – permanent hardness

(C) Temporary × permanent hardness

(D) Temporary ÷ permanent hardness

16. In the EDTA method, ________ drops of the indicator is used.

(A) 2 to 4 drops

(B) 2 to 3 drops

(C) 1 to 2 drops

(D) 5 to 8 drops

17. pH of __________ must be present in the EDTA solution in the buffer used.

(A) 20

(B) 15

(C) 5

(D) 10

18. At the pH of _______ the change in color is sharper.

(A) 5

(B) 10

(C) 15

(D) 20

19. CaCO₃ is given by __________ for the very hard water’s hardness.

(A) 100–200 ppm

(B) 100–300 ppm

(C) 200–300 ppm

(D) Above 300 ppm

20. Drinking water has the ________ pH value.

(A) 4.5–5.5

(B) 5.5–6.5

(C) 6.5–8.5

(D) 3.5–4.5

21. The amount of iron in drinking water can range about______

(A) 1–1.5 ppm

(B) 0.1–1 ppm

(C) 1–1.1 ppm

(D) 0.01–0.1 ppm

22. The amount of phosphate in drinking water can have the range of ______

(A) 5–10 ppm

(B) 15–20 ppm

(C) 10–15 ppm

(D) 20–25 ppm

23. The amount of organic matter in drinking water must be ______

(A) 1.0–2.0 ppm

(B) 0.2–1.0 ppm

(C) 2.0–3.0 ppm

(D) 3.0–4.0 ppm

24. Soluble salts turn into insoluble salts when the water is heated during the filtration in ______ and removed after filtration.

(A) Permanent hardness

(B) Temporary hardness

(C) Non-carbonate

(D) Non-alkaline

25. Magnesium limit in drinking water is about ___________

(A) 10–150 ppm

(B) 30–150 ppm

(C) 20–150 ppm

(D) 40–150 ppm

26. The amount of chloride in the drinking water range can be about __________

(A) 400–600 ppm

(B) 300–600 ppm

(C) 200–600 ppm

(D) 500–600 ppm

27. Permanent hardness in water does not produce the_____________

(A) Nitrates

(B) Bicarbonates

(C) Chlorides

(D) Sulphates

28. Select the process that does not remove the permanent hardness of water?

(A) Lime-soda

(B) Ion exchange process

(C) Zeolite process

(D) Heating

29. Choose one of the following options: Carbonate and bicarbonates are

(A) Alkaline

(B) Acidic

(C) Highly acidic

(D) Neutral