Question

Caustic soda is the common name for:
$
  (a){\text{ Mg(OH}}{{\text{)}}_2} \\
  (b){\text{ KOH}} \\
  {\text{(c) Ca(OH}}{{\text{)}}_2} \\
  (d){\text{ NaOH}} \\
 $

Answer 1

Hint – In this question use the concept that sodium hydroxide is another name of caustic soda. Use the name sodium hydroxide to find the right chemical composition for the name caustic soda. This approach will help getting the right option.

Complete answer:

As we know that sodium hydroxide is also known as soda or lye, or caustic soda.
At room temperature, sodium hydroxide is a white crystalline odorless solid that absorbs moisture from the air.
Its main use in the manufacture of pulp and paper, soap and detergents.
Other applications include water treatment, food, textiles etc.
And the chemical formula of sodium hydroxide is (NaOH).
So this is the required answer.
Hence option (D) is the correct answer.

Note – There is a confusion regarding the caustic soda and baking soda as to be the same. They are not the same because caustic soda is used in soap and detergents whereas baking soda is a cooking soda and it is a sodium bicarbonate. The formula for caustic soda is $NaOH$ whereas that of baking soda is $NaHC{O_3}$.