Q1. Fill in the blanks.
i. Burning of wood and coal causes ____________ of air.
ii. A liquid fuel, used in homes is _______________________________.
iii. Fuel must be heated to its _______________________ before it starts burning.
iv. Fire produced by oil cannot be controlled by __________.
v. The fuel may be ___________, ___________ or _________.
vi. Spontaneous forest fires are sometimes due to the _________ of the sun or due to ___________________.
i. Petrol is a liquid fuel. ________
ii. Spontaneous combustion of coal dust has resulted in many disastrous fires in coal mines. _________
iii. Cutting of trees leads to afforestation. __________
iv. Fuels differ in their efficiency and cost. _________
v. There are four different zones of a flame. _________
Q3. Name some of the substances which burn without producing a flame.
Q4. Name two substances having low ignition temperature.
Q5. Name two substances having high ignition temperature.
Q6. Name some common fuels.
Q7. Name some solid fuels.
Q8. Name some liquid fuels.
Q9. Name some gaseous fuels.
Q10. Which is the most common fire extinguisher?
Q11. Name one substance which burn in air at room temperature?
Q12. How are heat and light produced in the sun?
Q13. Name the term which 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?
Q15. Name the unit in which the calorific value of a fuel is expressed.
Q16. What is global warming?
Q17. What is fuel?
Q18. Which gas is produced due to incomplete combustion of fuel?
Q19. Name the fuel which is gradually replacing petrol and diesel in automobiles.
Q20. What is ignition temperature?
What is the ignition temperature of a substance?
Q21. What is meant by the calorific value of a fuel?