What is the chemical formula of washing soda?

Na₂CO₃.10H₂O

The correct answer is option 3. Na₂CO₃.10H₂O

Washing soda, also known as sodium carbonate decahydrate, has the chemical formula \(Na_2CO_3·10H_2O\). This means that each unit of washing soda is composed of two sodium ions \((Na^+)\), one carbonate ion \((CO_3^{2-})\), and ten water molecules \((H_2O)\).

The presence of water molecules in the formula indicates that washing soda is a hydrated compound. In its solid form, washing soda contains water molecules that are physically attached to the sodium carbonate molecules. These water molecules are loosely bound and can be released upon heating, resulting in the anhydrous form of sodium carbonate \((Na_2CO_3)\).

Washing soda is commonly used as a water softener, cleaning agent, and in various industrial processes due to its alkaline properties. When dissolved in water, it dissociates into sodium ions \((Na^+)\) and carbonate ions \((CO_3^{2-})\), which can help to remove dirt, grease, and stains from surfaces.

So, the correct chemical formula for washing soda is \(Na_2CO_3·10H_2O\), indicating its hydrated form with ten water molecules per formula unit