UPSC NDA I 2015 General Ability Paper

Concept:Washing soda is the common name for a specific chemical compound used in laundry and cleaning.Explanation:The compound known as washing soda is sodium carbonate, with the chemical formula $\mathrm{Na}_2\mathrm{CO}_3$.It is the sodium salt of carbonic acid and acts as a water softener and cleaning agent.Among the given options:Calcium carbonate ($\mathrm{CaCO}_3$) is used as a dietary supplement and antacid, not washing soda.Magnesium carbonate ($\mathrm{MgCO}_3$) is used to treat low magnesium levels in the blood.Potassium carbonate ($\mathrm{K}_2\mathrm{CO}_3$) is a different alkali salt.Also, sodium bicarbonate ($\mathrm{NaHCO}_3$) is known as baking soda, not washing soda.Therefore, only sodium carbonate matches the common name washing soda.Answer:Sodium Carbonate.