Level 1 — Basic Recall (1–10)

1. What is meant by “hard water”?

2. Name the two types of hardness.

3. Give one cause of temporary hardness.

4. Give one cause of permanent hardness.

5. Name a chemical used to soften hard water.

6. What is the ion responsible for temporary hardness?

7. What is the ion responsible for permanent hardness?

8. Define “water treatment.”

9. What is filtration?

10. What is chlorination?

Level 2 — Understanding (11–20)

11. Explain why temporary hardness can be removed by boiling.

12. Why can’t permanent hardness be removed by boiling?

13. Explain how ion-exchange resins soften water.

14. Describe how lime-soda process removes hardness.

15. What is flocculation?

16. Why is aeration used in water treatment?

17. Explain why hard water forms scum with soap.

18. Why is distilled water considered pure?

19. Explain the purpose of adding alum in water purification.

20. Describe the process of sedimentation.

Level 3 — Application (21–30)

21. Predict whether water containing Mg(HCO₃)₂ has temporary or permanent hardness.

22. Write the reaction for removing temporary hardness by boiling.

23. Explain how EDTA titration is used to determine water hardness.

24. Predict the effect of hard water on boilers and kettles.

25. Explain why ion-exchange resin eventually becomes “exhausted.”

26. Describe how activated carbon removes taste and odour.

27. Compare chlorination and ozonation for disinfection.

28. Predict hardness type in a water sample containing CaSO₄.

29. Explain how reverse osmosis purifies water.

30. Identify the ions removed by cation-exchange and anion-exchange resins.

Level 4 — Analysis (31–40)

31. Analyse why temporary hardness increases with CO₂ content in water.

32. Compare lime-soda method vs ion exchange in terms of cost and efficiency.

33. Discuss the disadvantages of excess chlorination.

34. Analyse how heavy metals can be removed from water.

35. Explain how pH affects solubility of metal ions in water.

36. Evaluate the environmental impact of softening water with sodium salts.

37. Explain the chemistry behind fluoridation of water.

38. Analyse scaling in industrial boilers using solubility principles.

39. Compare purification levels achieved by RO, distillation, and UV treatment.

40. Determine why brackish water requires special treatment before drinking.

Level 5 — Exam/Challenge (41–50)

41. Calculate hardness (in ppm CaCO₃) from EDTA titration data.

42. Propose a full treatment scheme for converting river water into potable water.

43. Analyze the complete chemical sequence in the lime-soda softening process.

44. Evaluate the thermodynamic aspects of scale formation in boilers.

45. Compare temporary vs permanent hardness using solubility product (Ksp) concepts.

46. Discuss the advantages and limitations of membrane filtration technologies.

47. Predict how industrial effluents change water chemistry and propose treatments.

48. Evaluate alternatives to chlorine in large-scale water purification.

49. Explain the ion-exchange equilibrium governing resin regeneration.

50. Propose a multi-stage water purification process for an industry requiring ultra-pure water (e.g., pharmaceuticals or electronics).