Question

Anhydrous sodium carbonate is commonly known as
    (A) Baking soda
    (B) Washing soda
    (C) Chalk
    (D) Paris white

Answer 1

Hint: It is an alkaline substance that is used for household cleaning, water softening etc. Solvay process is well known for the synthesis of this compound.

Complete step by step solution:
     - Sodium carbonate is an inorganic compound with the chemical formula $N{a}_{2}C{O}_3$.It exists in both hydrous and anhydrous forms.
     - Hydrous sodium carbonate contains water molecules. It has two forms. One is Sodium carbonate decahydrate ($N{a}_{2}C{O}_3.10H_{2}O$) and the other one is sodium carbonate monohydrate$N{a}_{2}C{O}_3.H_{2}O$ ($N{a}_{2}C{O}_3.H_{2}O$).
     - As we know, anhydrous sodium carbonate has no water molecules. It's just $N{a}_{2}C{O}_3$.
     - When the hydrated sodium carbonate is strongly heated, it decomposes into water and anhydrous sodium carbonate.
     - This anhydrous sodium carbonate is commonly known as washing soda. It is also called soda ash and soda crystals.
    - Sodium carbonate is water-soluble and when it is dissolved in water carbonic acid and $NaOH$ is formed.
    - Sodium carbonate is a strong base with pH = 10.5.
    - It is manufactured by different methods and the most famous one is the Solvay process. In this process carbon dioxide and ammonia is passed into a cold saturated solution of $NaCl$.
The answer is option (B). Anhydrous sodium carbonate is commonly known as washing soda.

Additional Information:
 Sodium carbonate has numerous applications such as in the manufacture of glass, paper, rayon, detergents and used for water softening, as food additive etc.

Note: There is a higher possibility for error since options seem confusing. Baking soda is sodium bicarbonate($NaHC{O}_3$), chalk is calcium carbonate($CaC{O}_3$) and paris white or plaster of paris is calcium sulfate($CaS{O}_4.{\displaystyle \frac{1}{2}}{H}_{2}O$) .