Find the percentage mass of water in washing soda crystals `Na_2CO_3 , 10H_2O.

Explanation

To find the percentage mass of water in washing soda crystals \( \text{Na}_2\text{CO}_3 \cdot 10\text{H}_2\text{O} \), we will follow these steps:

### Step 1: Calculate the molar mass of washing soda crystals \( \text{Na}_2\text{CO}_3 \cdot 10\text{H}_2\text{O} \)

1. **Identify the components:**
- Sodium (Na): 2 atoms
- Carbon (C): 1 atom
- Oxygen (O): 3 atoms from \( \text{Na}_2\text{CO}_3 \) and 10 atoms from \( 10\text{H}_2\text{O} \)
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