A municipal chemist reports that a water sample contains bicarbonates of calcium and magnesium. Which method will remove this type of hardness?
- A Permutit (base exchange) process only
- B Addition of sodium aluminate
- C Boiling followed by filtration ✓
- D Chlorination
Correct answer: C. Boiling followed by filtration
Explanation
Bicarbonates of calcium and magnesium constitute temporary hardness, which is removed simply by boiling: the bicarbonates decompose to insoluble carbonates that precipitate out. Permanent hardness from sulphates and chlorides requires the permutit process or lime soda treatment. Option C kills the distractor distinction: base exchange works on permanent hardness, not specifically on temporary hardness alone.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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