Question

Once in a market, there was a fire in cloth shop. When a lot of dry powder of a substance, X was released, the fire got extinguished. which of the following can be the substance 'X' ?

• A. Sodium bicarbonate $\left(NaHC{O}_3\right)$
• B. Potassium bicarbonate $\left(KHC{O}_3\right)$
• C. Sodium hydroxide $\left(NaOH\right)$
• D. Sodium chloride $\left(NaCl\right)$

Answer 1

Answer: (A), (B)

The correct options are
A Sodium bicarbonate $\left(NaHC{O}_3\right)$
B Potassium bicarbonate $\left(KHC{O}_3\right)$

The heat of fire decomposes sodium bicarbonate and potassium bicarbonate to produce carbon dioxide gas which covers the fire like a blanket. It cuts off supply of fresh air to the burning substance. Thus, fire gets extinguished.
Sodium hydroxide $\left(NaOH\right)$ and Sodium chloride $\left(NaCl\right)$ do not release carbon dioxide on heating. Hence, these compounds do not have fire extinguishing property.