Welcome To My School Study
Practice Class 8 Science Combustion and Flame MCQ Questions with Answers based on the latest NCERT syllabus. Learn about candle flame zones, oxygen in combustion, combustible substances, rapid combustion, and ignition temperature with detailed explanations, exam tips, and original NCERT-based solutions for CBSE and State Board students.
Do You Know
Chapter Information
Subject: Science
Class: 8
Chapter: Combustion and Flame
Question Type: Multiple Choice Questions (MCQs)
Difficulty Level: Easy to Moderate
Based On: Latest NCERT Syllabus
Introduction
Combustion is a chemical process in which a substance reacts with oxygen to produce heat and, often, light. It plays an important role in cooking, transportation, electricity generation, and many industrial processes. Understanding the properties of fuels, the structure of a flame, and different types of combustion helps students explain many everyday phenomena and use fuels safely.
What You Will Learn
✔ Conditions required for combustion
✔ Structure of a candle flame
✔ Role of oxygen in burning
✔ Combustible and non-combustible substances
✔ Types of combustion
✔ Ignition temperature
Why This Topic Is Important?
The chapter Combustion and Flame explains the scientific principles behind burning and fire safety. Questions from this chapter are commonly asked in CBSE, State Board, Olympiad, and scholarship examinations. These concepts also help students understand the efficient and safe use of fuels in daily life.
Exam Relevance
These questions are useful for:
✔ CBSE Exams
✔ State Board Exams
✔ School Tests
✔ Unit Tests
✔ Half-Yearly Exams
✔ Annual Exams
✔ Olympiad Preparation
✔ Scholarship Examinations
Q1. The middle zone of a candle flame is:
A) Blue
B) Black
C) Colorless
D) Yellow
Answer: Yellow
Concept Behind This Question
A candle flame has three distinct zones, each differing in colour, temperature, and the amount of combustion taking place.
Step-by-Step Solution
The middle zone of a candle flame appears yellow because combustion is incomplete in this region. Tiny unburnt carbon particles become hot and glow, giving the flame its bright yellow colour.
The outer blue zone is the hottest because complete combustion occurs there.
Therefore, the correct answer is: Yellow.
Exam Tip
Remember the candle flame zones:
- Inner Zone → Dark
- Middle Zone → Yellow
- Outer Zone → Blue and Hottest
Q2. Which gas is essential for combustion?
A) Hydrogen
B) Helium
C) Oxygen
D) Nitrogen
Answer: Oxygen
Concept Behind This Question
Combustion cannot continue without a sufficient supply of oxygen.
Step-by-Step Solution
Oxygen supports the burning process by reacting with combustible substances.
If the oxygen supply is reduced or cut off, combustion stops. This is why fire extinguishers often work by reducing the oxygen available to the fire.
Therefore, the correct answer is: Oxygen.
Exam Tip
Remember:
Fuel + Oxygen + Heat = Combustion
Q3. The substance that undergoes combustion is said to be:
A) Non-combustible
B) Combustible
C) Gaseous
D) Metallic
Answer: Combustible
Concept Behind This Question
Materials are classified based on whether they can burn.
Step-by-Step Solution
A combustible substance is one that can catch fire and burn in the presence of oxygen when heated to its ignition temperature.
Examples include:
- Wood
- Paper
- Petrol
- LPG
Materials such as glass and stone are generally non-combustible.
Therefore, the correct answer is: Combustible.
Exam Tip
Remember:
Combustible = Can Burn
Non-combustible = Does Not Burn Easily
Q4. Which of the following is an example of rapid combustion?
A) Burning of LPG
B) Digestion of food
C) Burning of wood
D) Rusting of iron
Answer: Burning of LPG
Concept Behind This Question
Rapid combustion is a type of combustion in which a substance burns quickly after ignition and produces heat and light.
Step-by-Step Solution
LPG burns rapidly when ignited in the presence of oxygen, producing a large amount of heat.
- Digestion is a slow biochemical process.
- Burning of wood is generally slower than LPG.
- Rusting is a slow oxidation process and is not combustion.
Therefore, the correct answer is: Burning of LPG.
Exam Tip
Remember the common types of combustion:
- Rapid Combustion → LPG
- Slow Combustion → Respiration
- Spontaneous Combustion → Without external flame
- Explosion → Sudden release of energy
Q5. The lowest temperature at which a substance catches fire is called:
A) Ignition temperature
B) Boiling point
C) Critical temperature
D) Melting point
Answer: Ignition temperature
Concept Behind This Question
Every combustible material requires a minimum temperature before it begins to burn.
Step-by-Step Solution
The ignition temperature is the minimum temperature at which a combustible substance starts burning in the presence of oxygen.
Below this temperature, combustion does not occur.
Therefore, the correct answer is: Ignition temperature.
Exam Tip
Remember:
Ignition Temperature = Minimum Temperature Required for Burning
Important Formulas & Concepts
1. Conditions Required for Combustion
Combustion takes place only when:
- A combustible substance (fuel) is present.
- Oxygen is available.
- The substance reaches its ignition temperature.
2. Zones of a Candle Flame
Inner Zone
- Dark
- Contains unburnt wax vapours
- Least hot
Middle Zone
- Yellow
- Incomplete combustion
- Moderately hot
Outer Zone
- Blue
- Complete combustion
- Hottest part of the flame
3. Combustible and Non-Combustible Substances
Combustible
- Wood
- Paper
- Petrol
- LPG
Non-combustible
- Glass
- Stone
- Sand
4. Types of Combustion
- Rapid Combustion
- Slow Combustion
- Spontaneous Combustion
- Explosion
5. Ignition Temperature
The minimum temperature at which a combustible substance starts burning in air.
6. Role of Oxygen
Oxygen supports combustion. Without oxygen, burning cannot continue.
Related Practice Questions
- Why is the outer zone of a candle flame the hottest?
- What are the three conditions necessary for combustion?
- Give two examples of combustible substances.
- What is the difference between rapid combustion and slow combustion?
- Why do firefighters use carbon dioxide to extinguish fires?
Mini Quiz Challenge
True or False
- The middle zone of a candle flame is yellow.
- Oxygen is necessary for combustion.
- Glass is a combustible material.
- LPG is an example of rapid combustion.
- Ignition temperature is the minimum temperature required for a substance to catch fire.
Exam Tips
✔ Learn the three zones of a candle flame.
✔ Remember the definition of ignition temperature.
✔ Understand the difference between combustible and non-combustible substances.
✔ Revise the different types of combustion with examples.
✔ Know the conditions required for combustion.
Quick Revision Notes
✔ Middle zone of the candle flame is yellow.
✔ Oxygen is essential for combustion.
✔ Combustible substances can burn.
✔ Burning of LPG is an example of rapid combustion.
✔ Ignition temperature is the minimum temperature needed for a substance to catch fire.
✔ The outer zone of a candle flame is the hottest.
Common Mistakes Students Make
❌ Confusing the yellow middle zone with the hottest outer zone.
❌ Thinking nitrogen supports combustion.
❌ Mixing up ignition temperature with melting point or boiling point.
❌ Assuming all burning processes occur at the same speed.
❌ Considering non-combustible materials as fuels.
Key Takeaways
- The middle zone of a candle flame appears yellow due to incomplete combustion.
- Oxygen is essential for the combustion process.
- Combustible substances burn when heated to their ignition temperature.
- Burning of LPG is a common example of rapid combustion.
- Ignition temperature is the minimum temperature required for a substance to start burning.
FAQs
1. Which zone of a candle flame is yellow?
The middle zone of a candle flame is yellow because incomplete combustion occurs there.
2. Which gas is necessary for combustion?
Oxygen is essential for combustion.
3. What is a combustible substance?
A combustible substance is a material that can catch fire and burn under suitable conditions.
4. What is rapid combustion?
Rapid combustion is a type of combustion in which a substance burns quickly after ignition, producing heat and light.
5. What is ignition temperature?
Ignition temperature is the lowest temperature at which a combustible substance starts burning in the presence of oxygen.
Conclusion
This Class 8 Science MCQ Practice Set covers the important concepts of the Combustion and Flame chapter, including candle flame zones, oxygen, combustible substances, rapid combustion, and ignition temperature. Regular practice of these NCERT-based questions strengthens conceptual understanding, improves scientific reasoning, and helps students perform confidently in school examinations and competitive tests.
NCERT Reference
Book: NCERT Science Class 8
Chapter: Chapter 6 – Combustion and Flame
Based On: Latest NCERT Curriculum (CBSE)
Related links
- Class 8 Maths Chapter 3 Understanding Quadrilaterals part-5
- Class 8 Maths Chapter 3 Understanding Quadrilaterals part-4
- Class 8 Maths Chapter 3 Understanding Quadrilaterals part-3
- Class 8 Maths Chapter 3 Understanding Quadrilaterals angle sum property
- Class 8 Maths Chapter 3 Understanding Quadrilaterals part-2
- Class 8 Maths Chapter 3 Understanding Quadrilaterals part-1
- Class 8 Maths Chapter 2 Linear Equations in One Variable part-11
- Class 8 Maths Chapter 2 Linear Equations in One Variable – part 10
- Class 8 Maths Chapter 2 Linear Equations in One Variable – Part 9
- Class 8 Maths Chapter 1 Rational Numbers- Part 10
Latest Posts
- Class 7 Social Science Chapter 1 Tracing Changes Through a Thousand Years
- Class 8 Social Science Chapter 1 How, When and Where
- Class 10 Social Science Chapter 1 The Rise of Nationalism in Europe
- Class 9 Social Science Chapter 1: The French Revolution
- Class 9 Maths Chapter 4 Linear Equations in Two Variables
Join Our Other Communities
Instagram , Youtube , Facebook
