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

Washing soda is the common name for sodium carbonate decahydrate, which has the chemical formula Na2CO3·10H2O [1]. It is a colorless, transparent crystalline compound that contains ten molecules of water of crystallization. In contrast, anhydrous sodium carbonate (Na2CO3) is known as soda ash [1]. Washing soda is widely used in glass, soap, and paper industries, as well as a cleaning agent for domestic purposes and for removing the permanent hardness of water [1]. Other options provided include NaHCO3, which is baking soda (sodium hydrogen carbonate), and NaOH, which is caustic soda (sodium hydroxide). The prefix 'deca-' in the formula Na2CO3·10H2O signifies the ten water molecules associated with the salt.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Uses of washing soda > p. 32