Previous Year Question
Which chemical, when released as a dry powder near a fire, produces CO₂?
A.
Calcium Carbonate
B.
Magnesium Oxide
C.
Potassium Phosphate
D.
Sodium Bicarbonate
Correct Answer: D
Detailed Solution
When sodium bicarbonate/sodium hydrogencarbonate (NaHCO₃) is heated, it decomposes and releases carbon dioxide (CO₂). According to NCERT, the reaction is:
2NaHCO₃ → Na₂CO₃ + H₂O + CO₂
The released CO₂ does not support combustion and helps extinguish fire by reducing the availability of oxygen around the burning material. NCERT also identifies sodium hydrogencarbonate as a substance used in soda-acid fire extinguishers.