In chemical terms , what are alums used for purifying water for drinking purposes ?

Options

A. Hydrated chlorides
B. Double nitrate
C. Double sulphates
D. Nitrates of aluminium

Explanation

**Step-by-Step Solution:**

1. **Definition of Alums**: Alums are a class of chemical compounds that are double sulfates of aluminum and another metal. They typically have the general formula M2(SO4)3·24H2O, where M represents a monovalent cation (like potassium or sodium).

2. **Properties of Alums**: Alums possess germicidal properties, which means they can kill or inhibit the growth of microorganisms. This property is crucial for water purification.

3. **Mechanism of Action**: When added to water, alums help in coagulation. They cause small particles and impurities in the water to clump together, forming larger particles called flocs. These flocs can then be easily removed from the water, leading to cleaner drinking water.

4. **Usage in Water Purification**: Due to their ability to coagulate impurities and their germicidal properties, alums are widely used in water treatment processes to purify drinking water. They help in reducing turbidity and removing harmful pathogens.

5. **Conclusion**: In summary, alums are used for purifying drinking water due to their double sulfate composition and their effectiveness as a germicide, which aids in coagulating impurities and killing harmful microorganisms.

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