Salt used in purification of water is.

Options

A. potash alum
B. epsom salt
C. green vitriol
D. blue vitriol

Answer

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks for the salt used in the purification of water.

2. **Recall Common Salts Used in Water Purification**: There are several salts that can be used for water purification, but one of the most common is Potash Alum.

3. **Define Potash Alum**: Potash Alum is a chemical compound that is used in water treatment processes. Its chemical formula is KAl(SO4)2·12H2O.

4. **Explain the Function of Potash Alum**: Potash Alum purifies water by a process called coagulation. It helps to remove suspended particles in the water.

5. **Describe the Coagulation Process**: The aluminum ions in Potash Alum carry a positive charge. When added to water, these ions attract negatively charged mud particles, causing them to clump together (coagulate).

6. **Result of Coagulation**: The clumped particles become larger and heavier, allowing them to sink to the bottom of the container. This makes it easier to remove the impurities from the water.

7. **Conclusion**: Therefore, the salt used in the purification of water is Potash Alum.

**Final Answer**: The salt used in the purification of water is Potash Alum (KAl(SO4)2·12H2O).

---