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Combustion and Flame Practice Questions

Class 8 · Science · 1092 free MCQs with instant results and detailed explanations.

1092
Total
337
Easy
538
Medium
217
Hard

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Topics in Combustion and Flame

Flame Structure 226
Fuel Efficiency 283
Types of Combustion 292
Combustion 291

Sample Questions from Combustion and Flame

Here are 10 sample questions. Start a quiz to get randomized questions with scoring.

Q1
Easy
What is the primary requirement for combustion to occur?
A. Oxygen
B. Water
C. Carbon Dioxide
D. Nitrogen
Show Answer & Explanation
Correct Answer: A
Oxygen is essential for combustion as it reacts with the fuel to produce heat and light.
Q2
Easy
Which of the following is not a product of combustion?
A. Water vapor
B. Carbon Dioxide
C. Oxygen
D. Heat
Show Answer & Explanation
Correct Answer: C
Oxygen is a reactant in combustion, not a product.
Q3
Easy
Which type of combustion occurs in an insufficient supply of oxygen?
A. Complete combustion
B. Incomplete combustion
C. Rapid combustion
D. Spontaneous combustion
Show Answer & Explanation
Correct Answer: B
Incomplete combustion occurs when there is not enough oxygen, leading to the production of carbon monoxide and soot.
Q4
Medium
Which of the following is necessary for combustion to occur?
A. Fuel
B. Water
C. Carbon Dioxide
D. Nitrogen
Show Answer & Explanation
Correct Answer: A
Fuel is needed for combustion, along with oxygen and heat. Without fuel, combustion cannot take place.
Q5
Medium
What type of combustion occurs when there is a limited supply of oxygen?
A. Complete combustion
B. Incomplete combustion
C. Rapid combustion
D. Spontaneous combustion
Show Answer & Explanation
Correct Answer: B
Incomplete combustion occurs when there isn't enough oxygen, leading to the production of carbon monoxide and soot.
Q6
Medium
Which of the following is a product of complete combustion of hydrocarbon fuels?
A. Carbon monoxide
B. Water
C. Soot
D. Unburnt fuel
Show Answer & Explanation
Correct Answer: B
The complete combustion of hydrocarbons produces carbon dioxide and water, unlike incomplete combustion which produces harmful products.
Q7
Medium
Which gas is commonly produced during incomplete combustion?
A. Oxygen
B. Nitrogen
C. Carbon Dioxide
D. Carbon Monoxide
Show Answer & Explanation
Correct Answer: D
Carbon monoxide is a byproduct of incomplete combustion, which occurs when there is not enough oxygen for complete combustion.
Q8
Hard
Which of the following is not a condition necessary for combustion to occur?
A. Fuel
B. Oxygen
C. Heat
D. Water
Show Answer & Explanation
Correct Answer: D
Water does not support combustion; it is often used to extinguish flames, while fuel, oxygen, and heat are essential for combustion.
Q9
Hard
In a combustion reaction, which of the following products is usually formed?
A. Acid
B. Base
C. Carbon Dioxide
D. Salt
Show Answer & Explanation
Correct Answer: C
Combustion of hydrocarbons typically produces carbon dioxide and water as products.
Q10
Hard
Which of the following fuels is known as a clean fuel?
A. Coal
B. Petrol
C. Natural Gas
D. Wood
Show Answer & Explanation
Correct Answer: C
Natural gas burns more cleanly than coal, petrol, or wood, producing fewer pollutants.

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Combustion and Flame — Class 8 Science Practice Questions Online

This page contains 1092 practice MCQs for the chapter Combustion and Flame in Class 8 Science. The questions are organized by difficulty — 337 easy, 538 medium, 217 hard — so you can choose the right level for your preparation.

Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit. This chapter covers 4 topics, giving you comprehensive coverage of the entire chapter.