Permutit is :

Options

A. Hydrated sodium aluminium silicate
B. Sodium hexaphosphate
C. Sodium bicarbonate
D. Calcium hydroxide

Answer

**Step-by-Step Solution:**

1. **Understanding Permutit**: Permutit is a type of ion exchanger used to soften water. It is specifically known as hydrated sodium aluminium silicate.

2. **Chemical Composition**: The chemical formula for permutit is Na2Al2Si2O8·xH2O, where x represents the number of water molecules associated with the compound.

3. **Role in Water Hardness**: Permutit is used to remove permanent hardness in water. Permanent hardness is caused by the presence of certain ions (like calcium and magnesium) in water. Permutit works by exchanging these hardness-causing ions with sodium ions, which do not contribute to hardness.

4. **Types of Ion Exchangers**: There are two main types of ion exchangers - inorganic and organic. Permutit falls under the category of inorganic ion exchangers.

5. **Preparation of Permutit**:
- **Natural Occurrence**: Permutit can occur naturally.
- **Artificial Preparation**: To prepare permutit artificially, a mixture of sodium carbonate (Na2CO3), silica (SiO2), and alumina (Al2O3) is fused together.
- After fusion, the mixture is washed with water, and the porous mass that remains is identified as permutit.

6. **Conclusion**: Based on the information, permutit is correctly identified as hydrated sodium aluminium silicate, confirming that the correct answer to the question is that permutit is hydrated sodium aluminium silicate.