Combustion and Flame MCQs for Class 8 with Answers

Practicing MCQs on Combustion and Flame Class 8 is one of the most effective ways to strengthen your understanding of NCERT Class 8 Science Chapter 6. These questions help students test how well they grasp the core concepts — from types of combustion, flame zones, and calorific value of fuels to fire safety precautions.

This Combustion and Flame Class 8 MCQ guide includes all the important objective-type questions that often appear in school exams and Olympiad-level tests. Each question is paired with a detailed answer and explanation to help you identify concepts you need to revise.

MCQs on What is Combustion & Its Types 

Practicing MCQs on types of combustion helps Class 8 students clearly understand how different materials burn and release heat. These questions are based on NCERT Class 8 Science Chapter 6 – Combustion and Flame, covering rapid, spontaneous, and explosion combustion with real-life examples.

1. Which of the following is a combustible substance?
(a) Glass
(b) Wood
(c) Stone
(d) Iron nail
Answer: (b) Wood

Explanation: Wood is a combustible substance because it can react with oxygen to produce heat and light. Glass, stone, and iron are non-combustible.

2. The process of a substance reacting with oxygen to give off heat is called:
(a) Melting
(b) Rusting
(c) Combustion
(d) Freezing
Answer: (c) Combustion

3. LPG burning in a gas stove is an example of:
(a) Spontaneous combustion
(b) Explosion
(c) Rapid combustion
(d) Slow combustion
Answer: (c) Rapid combustion

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4. Which of the following is an example of spontaneous combustion?
(a) Burning of a candle
(b) Bursting of firecrackers
(c) Forest fire
(d) Burning of matchstick
Answer: (c) Forest fire

5. Burning of coal in a slow, continuous manner is an example of:
(a) Rapid combustion
(b) Slow combustion
(c) Explosion
(d) Spontaneous combustion
Answer: (b) Slow combustion

6. Which of the following is NOT a combustible material?
(a) Paper
(b) Kerosene
(c) Water
(d) LPG
Answer: (c) Water

7. The combustion reaction in which heat and light are released suddenly is known as:
(a) Rapid combustion
(b) Explosion
(c) Spontaneous combustion
(d) Slow combustion
Answer: (b) Explosion

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8. The minimum temperature at which a substance catches fire is called:
(a) Boiling point
(b) Ignition temperature
(c) Melting point
(d) Freezing point
Answer: (b) Ignition temperature

9. Which of the following shows rapid combustion?
(a) Rusting of iron
(b) Burning of magnesium ribbon
(c) Self-burning of phosphorus
(d) Decomposition of wood
Answer: (b) Burning of magnesium ribbon

10. A substance that undergoes combustion to produce heat and light is known as:
(a) Fuel
(b) Catalyst
(c) Acid
(d) Base
Answer: (a) Fuel

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MCQs on Conditions Necessary for Combustion 

Understanding the conditions required for combustion is essential to mastering Class 8 Science Chapter 6 – Combustion and Flame. These MCQs on ignition temperature and conditions for combustion help students recall how oxygen, heat, and fuel work together to start and sustain burning.

1. Which gas is essential for combustion to take place?
(a) Nitrogen
(b) Carbon Dioxide
(c) Oxygen
(d) Hydrogen
Answer: (c) Oxygen

2. The lowest temperature at which a substance catches fire is called its:
(a) Melting point
(b) Boiling point
(c) Critical temperature
(d) Ignition temperature
Answer: (d) Ignition temperature

3. Why does a piece of paper burn easily while a piece of wood does not?
(a) Paper has a higher ignition temperature
(b) Wood has a higher ignition temperature
(c) Paper is not a combustible substance
(d) Wood is not a combustible substance
Answer: (b) Wood has a higher ignition temperature

4. Which of the following will not support combustion?
(a) Oxygen
(b) Carbon dioxide
(c) Air
(d) Hydrogen peroxide
Answer: (b) Carbon dioxide

5. Which condition is NOT essential for combustion?
(a) Presence of fuel
(b) Supply of oxygen
(c) Low ignition temperature
(d) Presence of water
Answer: (d) Presence of water

6. Why does kerosene catch fire faster than wood?
(a) It is lighter than air
(b) It has a lower ignition temperature
(c) It is non-combustible
(d) It produces less heat
Answer: (b) It has a lower ignition temperature

7. What happens if the supply of oxygen is cut off during combustion?
(a) The flame burns brighter
(b) The flame goes off
(c) The fuel burns faster
(d) The ignition temperature increases
Answer: (b) The flame goes off

8. Which of the following statements is true about ignition temperature?
(a) All substances have the same ignition temperature
(b) Substances with low ignition temperature catch fire easily
(c) Ignition temperature is always above 500°C
(d) Wood has lower ignition temperature than petrol
Answer: (b) Substances with low ignition temperature catch fire easily

9. Why is it easier to burn dry wood than wet wood?
(a) Water lowers the ignition temperature
(b) Water increases the ignition temperature
(c) Water increases the supply of oxygen
(d) Both burn at the same rate
Answer: (b) Water increases the ignition temperature

10. Which of the following will catch fire most easily?
(a) Wood
(b) Kerosene
(c) Coal
(d) Iron
Answer: (b) Kerosene

MCQs on How We Control Fire (Class 8 Science Chapter 6 – Combustion and Flame)

Learning how to control fire is an important part of Class 8 Science Chapter 6, as it connects science with real-life safety applications. These fire extinguisher objective-type questions help students understand how combustion can be stopped by removing heat, fuel, or oxygen — the three essential elements of fire.

Here are 10 important MCQs on Fire Control and Extinguishers with answers to help you revise effectively.

1. Which of the following is NOT a method to extinguish a fire?
(a) Adding fuel
(b) Removing oxygen supply
(c) Using water
(d) Cooling the substance below its ignition temperature
Answer: (a) Adding fuel

2. Water should not be used to extinguish which type of fire?
(a) Wood fire
(b) Paper fire
(c) Electrical fire
(d) All of the above
Answer: (c) Electrical fire

3. Which gas is commonly used in fire extinguishers?
(a) Oxygen
(b) Nitrogen
(c) Carbon Dioxide
(d) Helium
Answer: (c) Carbon Dioxide

4. How does carbon dioxide help in extinguishing fire?
(a) It reacts with fire to form water
(b) It cuts off oxygen supply
(c) It increases temperature
(d) It produces more carbon monoxide
Answer: (b) It cuts off oxygen supply

5. Why is sand used to put out oil fires?
(a) It absorbs the oil
(b) It prevents oxygen from reaching the fire
(c) It cools the oil
(d) It reacts with oil to form water
Answer: (b) It prevents oxygen from reaching the fire

6. Which of the following can be used safely on an electrical fire?
(a) Water
(b) Foam extinguisher
(c) CO₂ extinguisher
(d) Wet cloth
Answer: (c) CO₂ extinguisher

7. What is the primary purpose of a fire extinguisher?
(a) To increase air supply
(b) To stop the combustion process
(c) To add fuel
(d) To heat the object
Answer: (b) To stop the combustion process

8. Which method is used to stop combustion?
(a) Lowering the ignition temperature
(b) Cutting the oxygen supply
(c) Increasing fuel supply
(d) Heating the fuel
Answer: (b) Cutting the oxygen supply

9. A blanket is used to extinguish fire on a person because:
(a) It increases body temperature
(b) It removes oxygen contact
(c) It adds moisture
(d) It creates air pressure
Answer: (b) It removes oxygen contact

10. What type of fire extinguisher should be used for petroleum fires?
(a) Water
(b) Carbon dioxide
(c) Sand and foam-based
(d) Both (b) and (c)
Answer: (d) Both (b) and (c)

MCQs on Structure of a Flame (Class 8 Science Chapter 6)

Understanding the structure of a flame helps students visualize how combustion happens in layers. These MCQs on structure of a flame for Class 8 cover zones of the candle flame, colour variations, and their temperature differences — all directly from NCERT Class 8 Science Chapter 6.

Here are 10 important questions with answers for quick revision.

1. Which zone of a candle flame is the hottest?
(a) Innermost zone (black)
(b) Middle zone (yellow)
(c) Outermost zone (blue)
(d) All zones have the same temperature
Answer: (c) Outermost zone (blue)

2. The yellow, luminous part of a candle flame is due to:
(a) Complete combustion of wax vapours
(b) Unburnt wax vapours
(c) Incomplete combustion of wax vapours
(d) The colour of the wick
Answer: (c) Incomplete combustion of wax vapours

3. A goldsmith uses which zone of the flame for melting gold and silver?
(a) Innermost zone
(b) Outermost zone
(c) Middle zone
(d) Dark zone
Answer: (b) Outermost zone

4. Which zone of a flame produces the least heat?
(a) Blue zone
(b) Yellow zone
(c) Innermost zone
(d) Outer luminous zone
Answer: (c) Innermost zone

5. The colour of the hottest part of a candle flame is:
(a) Blue
(b) Yellow
(c) Orange
(d) Red
Answer: (a) Blue

6. What causes the blue outer zone of the flame?
(a) Unburnt carbon particles
(b) Complete combustion of vapours
(c) Presence of wax
(d) Moisture in air
Answer: (b) Complete combustion of vapours

7. Which part of the candle flame is moderately hot?
(a) Inner zone
(b) Middle luminous zone
(c) Outer zone
(d) Base of the wick
Answer: (b) Middle luminous zone

8. What does the black inner zone of the flame contain?
(a) Hot gases
(b) Unburnt wax vapours
(c) Carbon dioxide
(d) Air bubbles
Answer: (b) Unburnt wax vapours

9. Which zone of a flame emits light but less heat?
(a) Inner zone
(b) Middle luminous zone
(c) Outer blue zone
(d) None of these
Answer: (b) Middle luminous zone

10. The bluish outer zone of a flame shows:
(a) Partial combustion
(b) Incomplete combustion
(c) Complete combustion
(d) No combustion
Answer: (c) Complete combustion

MCQs on Fuels and Fuel Efficiency 

Understanding fuels and their efficiency is one of the most scoring topics in Class 8 Science Chapter 6 – Combustion and Flame. These Calorific Value of Fuels MCQs and LPG–CNG objective questions help students grasp how energy is produced and why cleaner fuels are preferred.

1. The amount of heat energy produced on complete combustion of 1 kg of a fuel is called its:
(a) Ignition temperature
(b) Calorific value
(c) Fuel efficiency
(d) Combustion value
Answer: (b) Calorific value

2. What is the unit of calorific value?
(a) kJ
(b) kg/kJ
(c) kJ/kg
(d) J/s
Answer: (c) kJ/kg

3. Which of the following is considered an ideal fuel?
(a) Has a very low calorific value
(b) Leaves behind a residue
(c) Is easily available and cheap
(d) Has a very low ignition temperature
Answer: (c) Is easily available and cheap

4. Which fuel has the highest calorific value among the following?
(a) Coal
(b) Wood
(c) LPG
(d) Kerosene
Answer: (c) LPG

5. Which of the following is a clean fuel?
(a) Diesel
(b) Petrol
(c) CNG
(d) Kerosene
Answer: (c) CNG

6. The efficiency of a fuel depends on its:
(a) Colour and density
(b) Calorific value
(c) Price
(d) Source of origin
Answer: (b) Calorific value

7. LPG is preferred as a household fuel because:
(a) It has low ignition temperature
(b) It has a high calorific value and burns without smoke
(c) It is solid and easy to store
(d) It produces ash after burning
Answer: (b) It has a high calorific value and burns without smoke

8. Which of the following is NOT a characteristic of a good fuel?
(a) High calorific value
(b) Produces more smoke
(c) Easy to transport and store
(d) Low cost and availability
Answer: (b) Produces more smoke

9. The calorific value of CNG is approximately:
(a) 10 kJ/kg
(b) 5000 kJ/kg
(c) 50,000 kJ/kg
(d) 55,000 kJ/kg
Answer: (d) 55,000 kJ/kg

10. The fuel efficiency of a vehicle depends on:
(a) Type of tyres
(b) Type of fuel used
(c) Colour of the vehicle
(d) Size of engine only
Answer: (b) Type of fuel used

MCQs on Harmful Effects of Burning Fuels 

Burning fuels like coal, diesel, and petrol produces harmful gases that cause air pollution, acid rain, and global warming. These MCQs on incomplete combustion and air pollution will help students understand the environmental impact of fuel usage.

1. Incomplete combustion of fuels like coal and petroleum releases which poisonous gas?
(a) Carbon dioxide
(b) Carbon monoxide
(c) Sulphur dioxide
(d) Oxygen
Answer: (b) Carbon monoxide

2. The burning of coal and diesel releases sulphur dioxide, which can lead to:
(a) Global warming
(b) Acid rain
(c) Smog
(d) Ozone depletion
Answer: (b) Acid rain

3. Which harmful gas is released during incomplete combustion of fuels?
(a) Carbon dioxide
(b) Methane
(c) Carbon monoxide
(d) Nitrogen
Answer: (c) Carbon monoxide

4. Which of the following gases contributes most to global warming?
(a) Sulphur dioxide
(b) Carbon dioxide
(c) Carbon monoxide
(d) Nitrogen
Answer: (b) Carbon dioxide

5. Acid rain damages:
(a) Buildings and crops
(b) Ozone layer
(c) Soil fertility only
(d) Plastic materials
Answer: (a) Buildings and crops

6. Which of the following fuels causes the most pollution?
(a) CNG
(b) Diesel
(c) LPG
(d) Biogas
Answer: (b) Diesel

7. Which of the following is a result of incomplete combustion?
(a) Blue flame
(b) Yellow smoky flame
(c) White flame
(d) Invisible flame
Answer: (b) Yellow smoky flame

8. Carbon monoxide is dangerous because:
(a) It causes skin diseases
(b) It combines with haemoglobin and reduces oxygen supply
(c) It cools the body temperature
(d) It increases heart rate
Answer: (b) It combines with haemoglobin and reduces oxygen supply

9. Which fuel is known as a clean fuel?
(a) Coal
(b) CNG
(c) Kerosene
(d) Diesel
Answer: (b) CNG

10. How can the emission of harmful gases from vehicles be reduced?
(a) By using unleaded petrol
(b) By using poor-quality fuel
(c) By removing silencer
(d) By using more diesel vehicles
Answer: (a) By using unleaded petrol

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