Q1. Fill in the blanks.
Burning of wood and coal causes pollution
A liquid fuel, used in homes is Liquified
Petroleum Gas (LPG).
Fuel must be heated to its ignition
temperature before it starts burning.
Fire produced by oil cannot be controlled
The fuel may be solid, liquid
Spontaneous forest fires are sometimes due
to the heat of the sun or due to lightning strike.
Petrol is a liquid fuel. True
Spontaneous combustion of coal dust has
resulted in many disastrous fires in coal mines. True
Cutting of trees leads to afforestation. False
Fuels differ in their efficiency and cost. True
There are four different zones of a flame. False
Q3. Name some of the substances which burn without producing a
Ans. Coal and Charcoal
Q4. Name two substances having low ignition temperature.
Ans. paper and white phosphorus
Q5. Name two substances having high ignition temperature.
Ans. coal and log of wood
Q6. Name some common fuels.
Ans. wood, charcoal, petrol and kerosene
Q7. Name some solid fuels.
Ans. wood, charcoal, coal, coke and cow-dung cakes
Q8. Name some liquid fuels.
kerosene, petrol and diesel
Q9. Name some gaseous fuels.
natural gas, petroleum gas, biogas and coal gas
Q10. Which is the most common fire extinguisher?
Ans. The most common fire extinguisher is water.
Q11. Name one substance which burn in air at room temperature?
burns in air at room temperature.
Q12. How are heat and light produced in the sun?
Ans. In the sun, heat and light are produced by
Q13. Name the term which is used to express the efficiency of a
term Calorific value is used to express the efficiency of a fuel.
Q14. Describe one method of putting out a fire caused by burning
wood or paper.
How will you put out a fire caused by burning wood or paper?
Ans. Water can be used when things like wood and paper
are on fire.
Q15. Name the unit in which the calorific value of a fuel is
Ans. The calorific value of a fuel is expressed in a
unit called kilojoule per kg (kJ/kg).
Q16. What is global warming?
Ans. Global warming is the rise in temperature of the
atmosphere of the earth.
Q17. What is fuel?
Ans. The substance that undergoes combustion is said
to be combustible. It is also called a fuel.
Q18. Which gas is produced due to incomplete combustion of fuel?
Ans. Incomplete combustion of fuels produces a very
poisonous gas called carbon monoxide.
Q19. Name the fuel which is gradually replacing petrol and
diesel in automobiles.
Ans. The use of diesel and petrol as fuels in
automobiles is being replaced by CNG (Compressed Natural Gas).
Q20. What is ignition temperature?
What is the ignition temperature of a substance?
lowest temperature at which a substance catches fire is called its ignition
Q21. What is meant by the calorific value of a fuel?
Ans. The amount of heat energy produced on complete
combustion of 1 kg of a fuel is called its calorific value.