Which one of the following is the chemical formula of Washing soda ?

Options

A. `NaHCO_(3)`
B. `Na_2CO_(3).10H_(2)O`
C. `Na_2CO_(3).5H_(2)O`
D. NaOH

Explanation

To determine the chemical formula of washing soda, we can follow these steps:

### Step 1: Understand the Options
We are given four options:
1. NaHCO3
2. Na2CO3.10H2O
3. Na2CO3.5H2O
4. NaOH

### Step 2: Identify the Correct Formula
Washing soda is commonly known as sodium carbonate with a specific hydration state. The correct formula for washing soda is:
- **Na2CO3.10H2O**

### Step 3: Explanation of the Formula
- **Na2CO3**: This part of the formula represents sodium carbonate.
- **10H2O**: This indicates that there are 10 molecules of water of crystallization associated with sodium carbonate, making it washing soda.

### Step 4: Conclusion
Thus, the chemical formula of washing soda is **Na2CO3.10H2O**.

---