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 the substance extinguish the fire ?
(c) Name another substance which behaves like X.
(a) 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 supply of air to the burning substance. Due to this the fire gets extinguished.
(c) Potassium hydrogen carbonate.
How does carbon dioxide help in putting off fire ?
Give reason for the following :
Paper by itself catches fire easily where as a piece of paper wrapped around an aluminium pipe does not.
An electric spark is struck between two electrodes placed near each other in a closed tank full of petrol. Will the petrol catch fire ? Explain your answer.
What type of combustion is represented by :
(a) burning of white phosphorus in air at room temperature ?
(b) burning of LPG in a gas stove ?
(c) ignition of a cracker ?
(d) burning of coal dust in a coal mine ?
