i. Burning of wood and coal causes pollution of air.
ii. A liquid fuel, used in homes is Liquified Petroleum Gas (LPG).
iii. Fuel must be heated to its ignition temperature before it starts burning.
iv. Fire produced by oil cannot be controlled by water.
v. The fuel may be solid, liquid or gas.
vi. Spontaneous forest fires are sometimes due to the heat of the sun or due to lightning strike.
i. Petrol is a liquid fuel. True
ii. Spontaneous combustion of coal dust has resulted in many disastrous fires in coal mines. True
iii. Cutting of trees leads to afforestation. False
iv. Fuels differ in their efficiency and cost. True
v. There are four different zones of a flame. False
Ans. Coal and Charcoal
Ans. paper and white phosphorus
Ans. coal and log of wood
Ans. wood, charcoal, petrol and kerosene
Ans. wood, charcoal, coal, coke and cow-dung cakes
Ans. kerosene, petrol and diesel
Ans. natural gas, petroleum gas, biogas and coal gas
Ans. The most common fire extinguisher is water.
Ans. Phosphorus burns in air at room temperature.
Ans. In the sun, heat and light are produced by nuclear reactions.
Ans. The term Calorific value is used to express the efficiency of a fuel.
Ans. Water can be used when things like wood and paper are on fire.
Ans. The calorific value of a fuel is expressed in a unit called kilojoule per kg (kJ/kg).
Ans. Global warming is the rise in temperature of the atmosphere of the earth.
Ans. The substance that undergoes combustion is said to be combustible. It is also called a fuel.
Ans. Incomplete combustion of fuels produces a very poisonous gas called carbon monoxide.
Ans. The use of diesel and petrol as fuels in automobiles is being replaced by CNG (Compressed Natural Gas).
Ans. The lowest temperature at which a substance catches fire is called its ignition temperature.
Ans. The amount of heat energy produced on complete combustion of 1 kg of a fuel is called its calorific value.
Download to practice offline.