How many water molecule(s) is/are present in microcosmic salt ?

Explanation

**Step-by-Step Solution:**

1. **Identify the Compound**: The first step is to recognize what microcosmic salt is. Microcosmic salt is known as sodium ammonium hydrogen phosphate.

2. **Write the Chemical Formula**: The chemical formula for microcosmic salt is NaNH₄HPO₄.

3. **Determine the Hydration State**: Microcosmic salt is commonly found in the form of a hydrate. Specifically, it is a tetrahydrate.

4. **Understand Tetrahydrate**: The term "tetrahydrate" indicates that there are 4 water molecules associated with each formula unit of the salt.

5. **Write the Full Formula**: The complete formula for microcosmic salt, including the water of hydration, is NaNH₄HPO₄·4H₂O.

6. **Conclusion**: Therefore, the number of water molecules present in microcosmic salt is 4.

**Final Answer**: Microcosmic salt contains 4 water molecules.

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