When a lot of dry powder of a substance X is released over a fire, the fire gets extinguished.
(a) Name the substance X.
(b) How does this substance extinguish the fire?
(c) Name another substance which behaves like X.

(a) Sodium bicarbonate (sodium hydrogen carbonate)

(b) The heat of fire decomposes sodium bicarbonate to produce carbon dioxide gas. This carbon dioxide covers the fire like a blanket and cuts off the supply of fresh air to the burning substance. Due to this, the fire gets extinguished.

(c) Potassium bicarbonate (or Potassium hydrogen carbonate)