Combustion and Flame Class 8 MCQ Questions

MCQ on Combustion and Flame Class 8

Choose the correct answer.

Question 1.
Which of the following burns without flame ?
A) candle
B) LPG
C) petrol
D) coal
Answer:
D) coal

Question 2.
Which gas causes suffocating ?
A) carbon monoxide
B) carbon dioxide
C) sulphur dioxide
D) nitrogen dioxide
Answer:
C) sulphur dioxide

Question 3.
When Magnesium burns, it forms
A) magnesium oxide
B) magnesium dioxide
C) magnesium chloride
D) magnesium
Answer:
A) magnesium oxide

Question 4.
Which gas causes acid rains ?
A) carbon monoxide
B) sulphur dioxide
C) nitrogen dioxide
D) B and C
Answer:
D) B and C

Question 5.
The rise in temperature of the atmosphere of the earth is
A) Global warming
B) Global atmosphere
C) Global village
D) Acid rains
Answer:
A) Global warming

Question 6.
A chemical process in which a substance reacts with …………….. to give off heat is called combustion.
A) coal
B) carbon dioxide
C) oxygen
D) water
Answer:
C) oxygen

Question 7.
Combustion takes place with
A) flame
B) glow
C) neither flame nor glow
D) either flame or glow
Answer:
D) either flame or glow

Question 8.
Which of the following is non-combustible ?
A) iron nail
B) paper
C) wood
D) petrol
Answer:
A) iron nail

Question 9.
Heat and light are released in the sun by the process of
A) combustion
B) nuclear reaction
C) A and B
D) neutralization
Answer:
B) nuclear reaction

Question 10.
The lowest temperature at which a substance catches fire is called its ……………… temperature.
A) boiling
B) melting
C) ignition
D) evaporation
Answer:
C) ignition

Question 11.
Matchstick head contains
A) antimony trisulphide
B) potassium chlorate
C) white phosphorus
D) all
Answer:
D) all

Question 12.
Which of the following substances in the matchstick is more dangerous ?
A) antimony trisulphide
B) potassium chlorate
C) white phosphorus
D) glue
Answer:
C) white phosphorus

Question 13.
The rubbing surface of the match box contains ………………
A) antimony trisulphide
B) potassium chlorate
C) red phosphorus
D) above all
Answer:
C) red phosphorus

Question 14.
Which of the following catches fire at room temperature ?
A) wood
B) kerosene
C) LPG
D) none
Answer:
D) none

Question 15.
Inflammable substances
A) low ignition temperature
B) high ignition temperature
C) no ignition temperature
D) none
Answer:
A) low ignition temperature

Question 16.
Which of the following is not an inflammable substance ?
A) alcohol
B) petrol
C) LPG
D) wood
Answer:
D) wood

Question 17.
Which of the following is an essential requirements for producing fire ?
A) fuel
B) air
C) heat
D) above all
Answer:
D) above all

Question 18.
The following substance supply the essential oxygen to produce fire
A) fuel
B) air
C) heat
D) above all
Answer:
B) air

Question 19.
What is the basic job of a fire extinguisher ?
A) to cut off the supply of air
B) to bring down the temperature of the fuel
C) both A and B
D) none
Answer:
C) both A and B

Question 20.
Which of the following is suitable for fire accidents caused by electricity ?
A) water
B) blanket
C) CO₂
D) above all
Answer:
C) CO₂

Question 21.
Which gas is containing in the given fire extinguisher ?

A) water vapour
B) O₂
C) CO₂
D) mixer of all
Answer:
C) CO₂

Question 22.
Alternative chemical which produce CO₂ gas ………………..
A) sodium bicarbonate
B) potassium bicarbonate
C) A or B
D) sodium chloride
Answer:
C) A or B

Question 23.
Phosphorus is an example of …………………. combustion.
A) spontaneous
B) rapid
C) slow
D) neutal
Answer:
A) spontaneous

Question 24.
Cause of forest fire …………………..
A) the heat of the sun
B) lightning strike
C) camp fires
D) above all
Answer:
D) above all

Question 25.
Which of the following is an example of explosion ?
A) matchsticks
B) fire works
C) CO₂ gas
D) cow dung cakes
Answer:
B) fire works

Question 26.
Explosion can also take place if ……………… is applied on the cracker.
A) pressure
B) water
C) A or B
D) oil
Answer:
A) pressure

Question 27.
The zone of unburnt fuel is
A) outermost
B) innermost
C) middle
D) above all
Answer:
B) innermost

Question 28.
Hottest part in the flame is
A) outermost
B) innermost
C) middle
D) above all
Answer:
A) outermost

Question 29.
The colour of complete burning part of the flame is ………………
A) blue
B) red
C) yellow
D) above all
Answer:
A) blue

Question 30.
The zone which is blown by the goldsmith to heat the gold
A) outer most
B) inner most
C) middle
D) above all
Answer:
A) outer most

Question 31.
Black colour appears in the flame of a candle at
A) outer most
B) inner most
C) middle
D) above all
Answer:
B) inner most

Question 32.
The property of good fuel is ……………..
A) cheap
B) burns easily in the air
C) large amount of heat
D) above all
Answer:
D) above all

Question 33.
Ideal fuel is
A) petrol
B) naphtha
C) LPG
D) none
Answer:
D) none

Question 34.
The amount of heat energy produced on complete combustion of 1 kg of a fuel is called its ……………
A) temperature
B) calorific value
C) combustion value
D) mass
Answer:
B) calorific value

Question 35.
The units of calorific value are
A) kg/J
B) KJ/sec
C) kJ/kg
D) Kg/ kelvin
Answer:
C) kJ/kg

Question 36.
Which of the following fuel leads to deforestation ?
A) cow dung cakes
B) LPG
C) wood
D) kerosene
Answer:
C) wood

Question 37.
Which gas among the following is more dangerous ?
A) carbon monoxide
B) carbon dioxide
C) sulphur dioxide
D) nitrogen dioxide
Answer:
A) carbon monoxide

Question 38.
Which gas causes global warming ?
A) carbon monoxide
B) carbon dioxide
C) sulphur dioxide
D) nitrogen dioxide
Answer:
C) sulphur dioxide

Question 39.
What information does the figure gives us ?

A) Necessity of a$r for burning
B) Ignition temperature
C) Combustion
D) Structure of flame
Answer:
A) Necessity of a$r for burning

Question 40.
In which situations we are misusing the fuel resources while cooking in our daily life ?
A) Cooking with out lid
B) Using more water while cooking
C) Leakages in pipes, burners and regu-lators
D) All the above
Answer:
D) All the above

Question 41.
Observe the following graph.
Which have same calorific value ?

A) Coal, Diesel
B) Coal, Petrol
C) Hydrogen, Diesel
D) Petrol, Diesel
Answer:
D) Petrol, Diesel

Question 42.
Clothes catch fire, the best way to extinguish the fire is to
A) Throw water on the clothes
B) Use hre extinguisher
C) Cover the person with a woolen blanket
D) Cover the person with a polythene sheet
Answer:
B) Use hre extinguisher

Question 43.
Which of the following is an example of rapid combustion ?
i) burning of food in our body
ii) burning of LPG
iii) matchsticks catching fire

A) only i
B) only iii
C) only ii and iii
D) all – i, ii and iii
Answer:
C) only ii and iii

Question 44.
If you pour soda into a bowl that has a lit candle, the flame will be put out.
This is because
A) the oxygen in the soda puts the fire out
B) the soda reacts with the wax and removes the fuel
C) the carbon dioxide from the soda puts the fire out
D) The flame will not be put out, it will start burning more brightly
Answer:
C) the carbon dioxide from the soda puts the fire out

Fill in the blanks.

1. The substances which burn in air are called ………………….. .
Answer:
combustible

2. ………………….. is essential for combustion.
Answer:
Oxygen (in air)

3. During the process of combustion, ………………….. are given out.
Answer:
heat and light

4. ………………….. is the lowest temperature at which a combustible substance catches fire.
Answer:
Ignition temperature

5. Inflammable substances have very ………………….. ignition temperature.
Answer:
low

6. Fire can be controlled by removing ………………….. requirements essential for producing fire.
Answer:
one or more

7. ………………….. is commonly used to control fires.
Answer:
Water

8. ………………. cannot be used to control fires involving electrical equipment or oils.
Answer:
Water

9. There are various types of combustions such as ………………….. spontaneous combustion and explosion.
Answer:
rapid cumbustion

10. There are three different zones of a flame ………………….., luminous zone and non-
luminous zone.
Answer:
dark zone

11. An ………………….. fuel is cheap, readily available, readily combustible and easy to transport.
Answer:
Ideal

12. ………………….. does not produce gases or residues that pollute the environment.
Answer:
Ideal fuel

13. Fuels differ in their ………………….. and ………………….. .
Answer:
efficiency, cost

14. Fuel efficiency is expressed in terms of its ………………….. which is expressed in units
of kilojoule per kg.
Answer:
calorific value

15. ………………….. carbon particles in air are dangerous pollutants causing respiratory problems.
Answer:
Unburnt

16. Incomplete combustion of a fuel gives poisonous ………………….. gas.
Answer:
carbon monoxide

17. Increased percentage of ………………….. in air has been linked to global warming.
Answer:
carbon dioxide

18. Oxides of sulphur and nitrogen produced by the burning of coal, diesel and petrol cause ………………….. which is harmful for crops, buildings and soil.
Answer:
acid rain

8th Class Physical Science Bit Bank