Types of Combustion MCQs
Types of Combustion MCQs Class 8
Class: CBSE Class 8
Subject: Science
Section: Section 6 – Combustion and Flame
Topic: Types of Combustion MCQs
Board: CBSE Board Examinations
Subject: Science
Section: Section 6 – Combustion and Flame
Topic: Types of Combustion MCQs
Board: CBSE Board Examinations
1. Combustion that occurs with a sudden release of heat and light is called:
Answer: b) Rapid combustion
Rapid combustion is a type of combustion in which a substance burns quickly when heat is supplied, producing heat and light immediately.
Rapid combustion is a type of combustion in which a substance burns quickly when heat is supplied, producing heat and light immediately.
2. Burning of LPG in a gas stove is an example of:
Answer: b) Rapid combustion
LPG burns instantly when ignited, producing heat and light quickly, hence it is rapid combustion.
LPG burns instantly when ignited, producing heat and light quickly, hence it is rapid combustion.
3. Combustion that occurs without external heat is called:
Answer: c) Spontaneous combustion
Spontaneous combustion occurs when substances catch fire on their own due to low ignition temperature.
Spontaneous combustion occurs when substances catch fire on their own due to low ignition temperature.
4. White phosphorus is stored in water because it:
Answer: c) Catches fire spontaneously
White phosphorus has very low ignition temperature and catches fire in air, so it is stored under water.
White phosphorus has very low ignition temperature and catches fire in air, so it is stored under water.
5. Combustion that occurs very slowly without flame is:
Answer: c) Slow combustion
Slow combustion produces heat slowly and no flame is seen, e.g., respiration.
Slow combustion produces heat slowly and no flame is seen, e.g., respiration.
6. Respiration is an example of:
Answer: b) Slow combustion
Respiration releases energy slowly from food inside cells, hence it is slow combustion.
Respiration releases energy slowly from food inside cells, hence it is slow combustion.
7. Explosion is a combustion process that:
Answer: c) Releases heat, light and gases suddenly
Explosion produces large amounts of heat, light, sound and gases instantly.
Explosion produces large amounts of heat, light, sound and gases instantly.
8. Firecrackers bursting is an example of:
Answer: c) Explosion
Firecrackers release gases, heat and sound suddenly, which is characteristic of explosion.
Firecrackers release gases, heat and sound suddenly, which is characteristic of explosion.
9. Which type of combustion produces flame?
Answer: b) Rapid combustion
Rapid combustion usually produces flame due to quick burning of vapours.
Rapid combustion usually produces flame due to quick burning of vapours.
10. Rusting of iron is an example of:
Answer: c) Slow oxidation
Rusting is a very slow reaction with oxygen, releasing negligible heat.
Rusting is a very slow reaction with oxygen, releasing negligible heat.
11. Which combustion requires external heat to start?
Answer: b) Rapid combustion
Rapid combustion needs an external flame or spark to begin burning.
Rapid combustion needs an external flame or spark to begin burning.
12. Haystacks catching fire on hot days is due to:
Answer: c) Spontaneous combustion
Heat generated inside hay lowers ignition temperature causing self‑ignition.
Heat generated inside hay lowers ignition temperature causing self‑ignition.
13. Combustion producing least heat rate is:
Answer: c) Slow combustion
Energy is released gradually in slow combustion.
Energy is released gradually in slow combustion.
14. Matchstick burning is:
Answer: b) Rapid combustion
It burns quickly when ignited.
It burns quickly when ignited.
15. Gunpowder explosion is used in:
Answer: b) Mining
Explosives help break rocks quickly.
Explosives help break rocks quickly.
16. Combustion without flame occurs in:
Answer: c) Charcoal burning
Charcoal glows without flame.
Charcoal glows without flame.
17. Which combustion is most dangerous?
Answer: c) Explosion
Explosions cause massive destruction due to sudden energy release.
Explosions cause massive destruction due to sudden energy release.
18. Diesel engine combustion is:
Answer: b) Rapid combustion
Fuel burns quickly to produce power.
Fuel burns quickly to produce power.
19. Combustion in which fuel vapours burn is:
Answer: a) Rapid combustion
Flames form when vapours burn rapidly.
Flames form when vapours burn rapidly.
20. The key factor causing spontaneous combustion is:
Answer: b) Low ignition temperature
Substances with very low ignition temperature catch fire on their own.
Substances with very low ignition temperature catch fire on their own.