Question

What is the chemical formula of washing soda?

• A. Na\textsubscript{2}CO\textsubscript{3}.7H\textsubscript{2}O
• B. Na\textsubscript{2}CO\textsubscript{3}.5H\textsubscript{2}O
• C. Na\textsubscript{2}CO\textsubscript{3}.10H\textsubscript{2}O
• D. Na\textsubscript{2}CO\textsubscript{3}.H\textsubscript{2}O

Hint:

Washing soda is used for cleaning and water softening because it removes hardness.

Answer 1

The Correct Option is C

Step 1: Identification.
Washing soda is the decahydrate form of sodium carbonate.
Step 2: Formula.
Its correct chemical formula is Na\textsubscript{2}CO\textsubscript{3}.10H\textsubscript{2}O.
Step 3: Conclusion.
Thus, option (3) is correct.