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1 CHEMISTRY MCQS

Sodium Carbonate is commonly called ?

  • Plaster of Paris
  • Washing Soda
  • Common Salt
  • None of these
Correct Answer: B. Washing Soda

Detailed Explanation

Sodium carbonate (Na₂CO₃) is an important inorganic compound commonly known as Washing Soda. It appears as a white crystalline solid and is highly soluble in water. Washing soda has been used for centuries in households and industries due to its strong alkaline nature.


Why is it called Washing Soda?


Washing soda is mainly used as a cleaning agent because of its ability to remove dirt, grease, and oil. It softens hard water by precipitating calcium and magnesium salts, making detergents more effective. This is why it earned the common name Washing Soda.


Chemical Properties of Sodium Carbonate




  • Chemical Formula: Na₂CO₃




  • Nature: Strong base (alkaline compound)




  • Crystalline Form: Often found as Na₂CO₃·10H₂O (decahydrate)




  • Easily reacts with acids to release carbon dioxide (CO₂)




Difference from Other Substances (Incorrect Options)




  • Plaster of Paris (Option A): This is chemically Calcium Sulfate Hemihydrate (CaSO₄·½H₂O), used for making molds and casts, not related to sodium carbonate.




  • Common Salt (Option C): This is Sodium Chloride (NaCl), used in food seasoning and preservation, completely different from sodium carbonate.




  • None of these (Option D): Incorrect because the right answer is clearly Washing Soda.




Uses of Washing Soda




  1. Laundry & Cleaning: Removes grease, oil, and dirt.




  2. Water Softening: Prevents scum formation with soaps.




  3. Glass & Soap Industry: Important raw material in manufacturing.




  4. Neutralizing Acids: Used in laboratories and industry.




Key Facts




  • Washing soda is strongly alkaline and must be handled carefully.




  • It is different from Baking Soda (NaHCO₃), which is milder and used in cooking.




  • It helps maintain the pH balance in swimming pools.



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