Hydrated sodium aluminium silicate is ___________.

Answer

To solve the question "Hydrated sodium aluminium silicate is ___________", we need to identify the correct term that describes hydrated sodium aluminium silicate.

### Step-by-Step Solution:

1. **Identify the Chemical Formula**:
- The chemical formula for hydrated sodium aluminium silicate is given as Na2Al2Si2O8·xH2O. This indicates that it contains water molecules associated with its structure.

2. **Understand the Nature of the Compound**:
- Sodium aluminium silicate is classified as a zeolite. Zeolites are a group of minerals known for their porous structure and ability to exchange cations.

3. **Recognize the Properties of Zeolites**:
- Zeolites are characterized by their honeycomb-like structure, which allows them to act as selective catalysts. This property is significant in various chemical processes, including ion exchange.

4. **Consider the Ion Exchange Property**:
- When hydrated sodium aluminium silicate interacts with hard water, it can exchange sodium ions (Na+) with calcium (Ca²+) and magnesium (Mg²+) ions. This ion exchange property is a key characteristic of zeolites.

5. **Conclude the Answer**:
- Based on the information gathered, we can conclude that hydrated sodium aluminium silicate is a **zeolite**.

### Final Answer:
Hydrated sodium aluminium silicate is **a zeolite**.

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