The chapter Combustion and Flame deals with the science behind burning and the role of fuels in daily life. In this chapter students are going to learn about combustion, ignition temperature, and flame structure. The chapter also covers types of combustion and safety tips for handling fire.
This set of MCQs and match-the-following questions focuses on the key concepts of the chapter. It covers topics like calorific value, fire extinguishers, and the role of oxygen in combustion. The questions are simple, interactive, and designed for easy revision.
Class 8 Science Chapter 4 MCQ Online Test Questions and Answers
Question 1. Combustion is a process in which a substance reacts with:
a) Hydrogen
b) Oxygen
c) Nitrogen
d) Carbon dioxide
Answer:
b) Oxygen
Question 2. Substances that burn in air are called:
a) Non-combustible substances
b) Combustible substances
c) Metals
d) Alloys
Answer:
b) Combustible substances
Question 3. The lowest temperature at which a substance catches fire is known as:
a) Boiling point
b) Freezing point
c) Ignition temperature
d) Melting point
Answer:
c) Ignition temperature
Question 4. Which of the following is an example of an inflammable substance?
a) Water
b) Petrol
c) Sand
d) Glass
Answer:
b) Petrol
Question 5. Water cannot be used to extinguish fire caused by:
a) Wood
b) Paper
c) Petrol
d) Coal
Answer:
c) Petrol
Question 6. Which gas is released during incomplete combustion?
a) Oxygen
b) Carbon dioxide
c) Carbon monoxide
d) Nitrogen
Answer:
c) Carbon monoxide
Question 7. The colour of the hottest part of a flame is:
a) Yellow
b) Blue
c) Red
d) Black
Answer:
b) Blue
Question 8. The substance that does not form a flame when burned is:
a) Charcoal
b) Kerosene
c) Candle wax
d) Magnesium
Answer:
a) Charcoal
Question 9. The calorific value of LPG is approximately:
a) 17,000 kJ/kg
b) 33,000 kJ/kg
c) 55,000 kJ/kg
d) 60,000 kJ/kg
Answer:
c) 55,000 kJ/kg
Question 10. Which type of combustion occurs suddenly with heat, light, and sound?
a) Rapid combustion
b) Explosion
c) Spontaneous combustion
d) Slow combustion
Answer:
b) Explosion
Question 11. The main component of CNG is:
a) Propane
b) Methane
c) Ethane
d) Butane
Answer:
b) Methane
Question 12. Fire caused by electrical equipment is best extinguished using:
a) Water
b) Sand
c) Carbon dioxide
d) Petrol
Answer:
c) Carbon dioxide
Question 13. The chemical process involved in burning is:
a) Neutralisation
b) Oxidation
c) Reduction
d) Combustion
Answer:
d) Combustion
Question 14. Which zone of a candle flame has unburnt carbon particles?
a) Blue zone
b) Luminous zone
c) Dark zone
d) Outer zone
Answer:
b) Luminous zone
Question 15. Global warming is primarily caused by the increased concentration of:
a) Nitrogen
b) Oxygen
c) Carbon dioxide
d) Helium
Answer:
c) Carbon dioxide
Question 16. Which fuel has the highest calorific value?
a) Hydrogen
b) Petrol
c) LPG
d) Wood
Answer:
a) Hydrogen
Question 17. The combustion that occurs on its own without external heating is called:
a) Rapid combustion
b) Explosion
c) Spontaneous combustion
d) Slow combustion
Answer:
c) Spontaneous combustion
Question 18. In a fire extinguisher, carbon dioxide is stored as:
a) A gas
b) A liquid
c) Solid dry ice
d) Powder
Answer:
b) A liquid
Question 19. Which part of the flame is used by goldsmiths for melting gold and silver?
a) Luminous zone
b) Dark zone
c) Non-luminous zone
d) Inner zone
Answer:
c) Non-luminous zone
Question 20. Acid rain is caused by the oxides of:
a) Sulphur and nitrogen
b) Carbon and nitrogen
c) Oxygen and hydrogen
d) Carbon and oxygen
Answer:
a) Sulphur and nitrogen
Question 21. A good fuel produces:
a) Maximum smoke
b) High energy and minimal residue
c) No heat
d) Pollution
Answer:
b) High energy and minimal residue
Question 22. Which gas is used in fire extinguishers?
a) Nitrogen
b) Carbon dioxide
c) Oxygen
d) Methane
Answer:
b) Carbon dioxide
Question 23. The ignition temperature of a substance is:
a) Very high
b) Very low
c) Specific for each substance
d) Not required for combustion
Answer:
c) Specific for each substance
Question 24. The outermost zone of a flame is:
a) Hottest and blue
b) Coolest and yellow
c) Dark and hot
d) Black and cold
Answer:
a) Hottest and blue
Question 25. The burning of coal releases:
a) Sulphur dioxide
b) Carbon monoxide
c) Carbon dioxide
d) All of the above
Answer:
d) All of the above
Question 26. Which material forms a flame when burned?
a) Charcoal
b) Magnesium
c) Kerosene oil
d) Both b and c
Answer:
d) Both b and c
Question 27. Which is an example of rapid combustion?
a) Burning coal slowly
b) Lighting an LPG stove
c) Rusting of iron
d) Melting ice
Answer:
b) Lighting an LPG stove
Question 28. The dark zone of a flame contains:
a) Partially burnt fuel
b) Unburnt wax vapors
c) Fully burnt fuel
d) Oxygen
Answer:
b) Unburnt wax vapors
Question 29. Fire extinguishers for electrical fires contain:
a) Water
b) Sand
c) Carbon dioxide
d) Petrol
Answer:
c) Carbon dioxide
Question 30. Which zone of a flame has maximum temperature?
a) Outer zone
b) Luminous zone
c) Dark zone
d) Inner zone
Answer:
a) Outer zone
Question 31 – Match the Following
| Column A | Column B |
|---|---|
| 1. Ignition temperature | A. Produces carbon dioxide |
| 2. Rapid combustion | B. Very low ignition temperature |
| 3. Inflammable substances | C. Energy released during burning |
| 4. Calorific value | D. Lowest temperature for combustion |
| 5. Complete combustion | E. LPG burns instantly |
Answer:
| Column A | Correct Answer |
|---|---|
| 1. Ignition temperature | D. Lowest temperature for combustion |
| 2. Rapid combustion | E. LPG burns instantly |
| 3. Inflammable substances | B. Very low ignition temperature |
| 4. Calorific value | C. Energy released during burning |
| 5. Complete combustion | A. Produces carbon dioxide |
