CLASS: VIII COMBUSTION & FLAME
DPP
I. Multiple Choice Questions (MCQs)
Choose the correct option.
Question 1.
Which of the following fuels is used for running automobiles?
(a) CNG
(b) Petrol
(c) Both (a) and (b)
(d) Wood
Question 2.
Magnesium burns to form
(a) calcium carbonate
(b) magnesium oxide
(c) calcium oxide
(d) magnesium sulphate
Question 3.
Coal burns to produce
(a) calcium bicarbonate
(b) magnesium
(c) carbon dioxide
(d) oxygen
Question 4.
Name the chemical process in which a substance reacts with oxygen to give out heat.
(a) Reaction
(b) Junction
(c) Combustion
(d) All of these
Question 5.
The substance that undergoes combustion is said to be
(a) burning
(b) flame
(c) charcoal
(d) combustible
Question 6.
Combustible substances are also known as
(a) inflammable
(b) flaming
(c) illuminous
(d) non-flammable
Question 7.
Which of the following is a combustible?
(a) Stone piece
(b) Wood
(c) Glass
(d) None of these
Question 8.
In the sun, light and heat are produced by
(a) chemical reactions
(b) nuclear reactions
(c) burning reactions
(d) bunsen burner
Question 9.
Lowest temperature at which a substance catches fire is known as
(a) lowest temperature
(b) burning temperature
(c) ignition temperature
(d) flaming temperature
Question 10.
Long, long ago, which of the following trees was used to produce matchsticks?
(a) Mango
(b) Deodar
(c) Banyan
(d) Pine
Question 11.
Which chemical is used in the rubbing surface provided for matchsticks?
(a) Sulphur
(b) Gold
(c) Red phosphorus
(d) White phosphorus
Question 12.
Substances which 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
Question 13.
Which of the following is an example of inflammable substance?
(a) Iron
(b) Glass
(c) LPG
(d) Stone
Question 14.
Which of the following are required essentially for producing fire?
(a) Glass, coal, water
(b) Fuel, coal, straw
(c) Fire, wood, burner
(d) Fuel, air, heat
Question 15.
The most common element used as fire extinguisher is
(a) CO2
(b) oxygen
(c) phosphorous
(d) oxygen
Question 16.
Baking soda constitutes
(a) hydrogen chloride
(b) sodium oxide
(c) sodium bicarbonate
(d) oxygen
Question 17.
LPG means
(a) Liquefied Petroleum Gas
(b) Liquefied Petrol Gas
(c) Liquid Petrol Godown
(d) Liquid Petroleum Gas
Question 18.
Phosphorus burns at
(a) room temperature
(b) 100°C
(c) cool temperature
(d) any temperature
Question 19.
‘Firework’ is an example of
(a) rapid combustion
(b) explosion
(c) spontaneous combustion
(d) slow combustion
Question 20.
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
II. Fill in the Blanks
Fill in the blanks with suitable word/s.
1. The substance which vaporizes during burning gives _________ .
2. A good fuel should have _________ calorific value.
3. An example of slow combustion is _________.
4. _________ are substances that release energy on combustion.
5. The most common supporter of combustion is _________.
6. Magnesium burns to change into _________.
7. Wood is an example of _________ fuel.
8. _________ is an example of liquid fuel.
9. Carbon dioxide is _________ than oxygen.
10. Oxides of _________ and nitrogen causes acid rain.
11. The increase in amount of _________ gas in atmosphere results in global warming.
12. Inflammable substances have very low _________ temperature.
13. The _________ zone of a flame is the hottest.
14. During combustion, generally, _________ and _________ energies are produced.
15. LPG has a calorific value of _________ kJ/kg.
III. True or False
State whether the given statements are true or false.
1. Automobiles run only by using petrol.
2. CNG means ‘Connecting Neutral Gas’.
3. Coal burns with a flame.
4. Magnesium burns to produce magnesium oxide.
5. Combustion is a physical process.
6. The substance that undergoes combustion is said to be combustible.
7. Fuel may be solid, liquid or gas.
8. Wood is combustible.
9. A matchstick only contains white phosphorus.
10. Kerosene is an example of solid fuel.
11. For combustion, a substance must attain its ignition temperature.
12. The ignition temperature of phosphorus is 25°C.
13. LPG is an example of inflammable substances.
14. Water is a bad conductor of electricity.
15. Fuel, water and heat are three essential requirements for combustion.
16. The most common fire extinguisher is water.
17. Oxygen is heavier than C02.
18. The middle zone of a flame has yellow colour.
19. The calorific value of hydrogen is 1,50,000 kJ/kg.
20. Increase in nitrogen gas in atmosphere has led to ‘global warming’
IV. Answer the following questions
1. Give two examples of secondary fuels.
2. What is the calorific value of diesel?
3. What is global warming?
4. Which gaseous is used in our homes for cooking?
5. What is a flame?
6. What is a fire extinguisher? Write two types of fire extinguishers.
7. What is calorific value? Write its SI unit.
8. What are non-renewable fuels? Give two examples.
9. What are gaseous fuels? Give two examples.
10. What is slow combustion? Give two examples.
11. Ruby lights the burner with a lighter and noticed that the flame rises blue in colour.
Why the colour of the flame is blue?
12. Why the luminous zone is also called incomplete combustion?
13. Illustrate some brief description about solid fuels, liquid fuel and gaseous fuels.
14. Write three characteristics of an ideal fuel.
15. What happen if anyone inhale carbon monoxide gas?
16. Which gas is responsible of global warming and why?
17. Which compound is present in smoke released by the vehicles and what happen if the
smoke produces in an enormous value?
18. Write a general equation of chemical reaction for complete combustion.
19. Explain the zones of candle flame and also draw a well-labelled diagram
20. Write a short note about soda-fire extinguisher? Also draw its well-labelled diagram.
