The molecular formula of anhydrous compound A is 64. in the crystalline state its molecular weight is 100. the number of water molecules of crystallisation in the crystalline state is

Options

A. 1
B. 2
C. 3
D. 4

Explanation

To find the number of water molecules of crystallization in the crystalline state of compound A, follow these steps:

### Step-by-Step Solution:

1. **Identify the Molecular Weights**:
- The molecular weight of the anhydrous compound A is given as 64 g/mol.
- The molecular weight of the crystalline compound (which includes water) is given as 100 g/mol.

2. **Calculate the Weight of Water**:
- To find the weight of water present in the crystalline state, subtract the molecular weight of the anhydrous compound from the molecular weight of the crystalline compound.
\[ \text{Weight of water} = \text{Molecular weight of crystalline compound} - \text{Molecular weight of anhydrous compound} \]
\[ \text{Weight of water} = 100 \, \text{g/mol} - 64 \, \text{g/mol} = 36 \, \text{g/mol} \]

3. **Determine the Molecular Weight of Water**:
- The molecular weight of water (H₂O) is calculated as follows:
\[ \text{Molecular weight of H₂O} = 2 \times \text{(weight of H)} + \text{(weight of O)} = 2 \times 1 + 16 = 18 \, \text{g/mol} \]

4. **Calculate the Number of Water Molecules**:
- To find the number of water molecules of crystallization, divide the weight of water by the molecular weight of water.
\[ \text{Number of water molecules} = \frac{\text{Weight of water}}{\text{Molecular weight of water}} = \frac{36 \, \text{g/mol}}{18 \, \text{g/mol}} = 2 \]

5. **Conclusion**:
- The number of water molecules of crystallization in the crystalline state is 2.

### Final Answer:
The number of water molecules of crystallization in the crystalline state is **2**.