Question

After heating washing soda, the colour of residue left behind would be
A. Yellow
B. Black
C. Pink
D. White

Answer 1

Explanation:

after heating it white colour will be former

Answer 2

D. White

Explanation:

Washing soda, also known as sodium carbonate decahydrate contains water molecules in its crystals. The chemical formula of washing soda is Na2CO3.10H2O. When heated, the water molecules evaporate leaving behind anhydrous sodium carbonate (Na2CO3). Anhydrous sodium carbonate is a white powder. This process of loosing water of crystallization when exposed to air is called efflorescence.

Option D is the correct answer.