Q 1. Which of the following fuels is used for running automobiles?
(a) CNG
(b) Petrol
(c) Both (a) and (b)
(d) Wood
Q 2. Magnesium burns to form
(a) calcium carbonate
(b) magnesium oxide
(c) calcium oxide
(d) magnesium sulphate
Q 3. The substance that undergoes combustion is said to be
(a) burning
(b) flame
(c) charcoal
(d) combustible
Q 4. Combustible substances are also known as
(a) inflammable
(b) flaming
(c) illuminous
(d) non-flammable
Q 5. In the sun, light and heat are produced by
(a) chemical reactions
(b) nuclear reactions
(c) burning reactions
(d) bunsen burner
Q 6. Long, long ago, which of the following trees was used to produce matchsticks?
(a) Mango
(b) Deodar
(c) Banyan
(d) Pine
Q 7. Substances that have very low ignition temperature and can catch fire easily are called
(a) flammable substances
(b) inflammable substances
(c) combustible substances
(d) all of these
Q 8. Baking soda constitutes
(a) hydrogen chloride
(b) sodium oxide
(c) sodium bicarbonate
(d) oxygen
Q 9. Phosphorus burns at
(a) room temperature
(b) 100°C
(c) cool temperature
(d) any temperature
Q 10. The calorific value of ‘hydrogen’ is
(a) 50,000 kJ/kg
(b) 55,000 kJ/kg
(c) 1,50,000 kJ/kg
(d) 6,000 kJ/kg
Q 11. Fill in the blanks
- The substance which vapourises during burning gives ……………
- A good fuel should have …………… calorific value.
- An example of slow combustion is ……………
- …………… are substances that release energy on combustion.
- The most common supporter of combustion is ……………
Q 12. True or false
- Automobiles run only by using petrol.
- CNG means ‘Connecting Neutral Gas’.
- Coal burns with a flame.
- Magnesium burns to produce magnesium oxide.
- Combustion is a physical process.
Q 13. True or False
Column A | Column B |
1. Fire extinguisher | a. Natural gas |
2. Fossil fuel | b. Cooking gas |
3. Oxygen gas | c. Inflammable |
4. LPG | d. Carbon dioxide |
5. Alcohol | e. Supporter of combustion |
Q 14. What does magnesium burn to form?
Q 15. What is combustion?
Q 16. How does a matchstick catch fire?
Q 17. What are combustible and non-combustible substances?
Q 18. Define spontaneous combustion.
Q 19. Give two examples each of solid fuels, liquid fuels and gaseous fuels.
Q 20. Name the colours of the flames of following substances:
Barium,
arsenic,
sodium,
magnesium
Q 21. It is observed at petrol pumps and airports, that hydrocarbon fire extinguishers are used, instead of soda-acid fire extinguisher. Give reasons why.
Q 22. Explain complete combustion.
Q 23. Write in brief about the reasons of forest fires.
Q 24. If you hold a piece of iron wire with a pair of tongs inside a candle flame or a Bunsen burner flame, what will you observe? Will it produce a flame?
Q 25. Sourav was heating oil to fry potato chips. The cooking oil all of a sudden caught fire. He took water to pour on the fire to extinguish it. But meanwhile his mother came and switched off the gas and covered the wok completely with a plate.
Q 26. Make a model of a fire extinguisher. Place a short candle and a slightly taller candle in a small dish filled with baking soda. Place the dish at the bottom of a large bowl. Light both the candles. Then pour vinegar into the dish of baking soda. Take care. Do not pour vinegar on the candles. Observe the foaming reaction. What happens to the candles? Why? In what order?
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