How many water molecules are present in one molecule of washing soda ?

Options

A. `8`
B. `5`
C. `7`
D. `10`

Answer

To determine how many water molecules are present in one molecule of washing soda, we can follow these steps:

### Step 1: Identify the Chemical Formula
The first step is to know the chemical formula of washing soda. The formula for washing soda is:
\[ \text{Na}_2\text{CO}_3 \cdot 10 \text{H}_2\text{O} \]

### Step 2: Analyze the Formula
In the formula, the part \( 10 \text{H}_2\text{O} \) indicates the number of water molecules associated with one molecule of washing soda.

### Step 3: Count the Water Molecules
From the formula, we can see that there are 10 water molecules (H2O) attached to one molecule of washing soda.

### Step 4: Conclusion
Therefore, the number of water molecules present in one molecule of washing soda is:
\[ \text{10} \]

### Final Answer
The correct option is 10.

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