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Practice Class 9 Science Chapter 1 Matter in Our Surroundings MCQ Questions with Answers based on the latest NCERT syllabus. Solve important MCQs on latent heat of fusion, latent heat of vaporisation, particle motion, state changes, and intermolecular forces with detailed solutions for CBSE, State Board, Olympiad, and scholarship exams.
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Chapter Information
Subject: Science
Class: 9
Chapter: Matter in Our Surroundings
Question Type: Multiple Choice Questions (MCQs)
Difficulty Level: Easy to Moderate
Based On: NCERT Latest Syllabus (2026)
Introduction
Matter can change from one state to another when heat is supplied or removed. These changes involve important concepts such as latent heat, particle motion, and intermolecular forces. Understanding these ideas helps students explain many everyday phenomena scientifically.
What You Will Learn
✔ Latent heat of fusion
✔ Latent heat of vaporisation
✔ Effect of heating on particles
✔ Intermolecular forces
✔ Changes of state
✔ NCERT-based concepts
✔ Real-life applications
Why This Topic Is Important?
Latent heat and changes of state are among the most important concepts in this chapter. Questions based on these topics frequently appear in school examinations, Olympiads, scholarship tests, and competitive exams.
1. MCQ Questions with Detailed Solutions
Q1. The heat required to convert a solid into a liquid at its melting point is called:
A) Specific Heat
B) Latent Heat of Fusion
C) Latent Heat of Vaporisation
D) Thermal Energy
Answer
B) Latent Heat of Fusion
Concept Behind This Question
A solid absorbs heat during melting without any increase in temperature.
Step-by-Step Solution
- Ice melts at 0°C.
- During melting, temperature remains constant.
- The absorbed heat changes the state from solid to liquid.
- This heat is called latent heat of fusion.
Exam Tip
Fusion means melting of a solid.
Q2. Which of the following processes requires latent heat of vaporisation?
A) Ice changing into water
B) Water changing into steam
C) Steam changing into water
D) Water freezing into ice
Answer
B) Water changing into steam
Concept Behind This Question
Latent heat of vaporisation is required for liquid-to-gas conversion.
Step-by-Step Solution
- Water absorbs heat continuously.
- At the boiling point, it changes into steam.
- The heat used for this state change is latent heat of vaporisation.
Exam Tip
Vaporisation means liquid changing into gas.
Q3. What happens to the particles of matter when heat is supplied?
A) They stop moving
B) Their kinetic energy decreases
C) Their kinetic energy increases
D) Their size increases
Answer
C) Their kinetic energy increases
Concept Behind This Question
Heating increases particle motion.
Step-by-Step Solution
- Heat provides energy to particles.
- Particles move faster.
- Faster motion means higher kinetic energy.
Exam Tip
Temperature and kinetic energy are directly related.
Q4. Which state of matter has the weakest force of attraction between particles?
A) Solid
B) Liquid
C) Gas
D) All have equal attraction
Answer
C) Gas
Concept Behind This Question
Gas particles are far apart and attract each other very weakly.
Step-by-Step Solution
- Solids have strongest attraction.
- Liquids have moderate attraction.
- Gases have maximum intermolecular space.
- Therefore, gases have the weakest attraction.
Exam Tip
Weak attraction allows gases to spread rapidly.
Q5. Which change of state occurs when steam cools down?
A) Melting
B) Freezing
C) Condensation
D) Sublimation
Answer
C) Condensation
Concept Behind This Question
Cooling of a gas converts it into a liquid.
Step-by-Step Solution
- Steam is water in gaseous form.
- On cooling, steam loses energy.
- It changes into liquid water.
- This process is called condensation.
Exam Tip
Gas → Liquid = Condensation.
Important Formulas & Concepts
1. Latent Heat of Fusion
Heat required to convert a solid into liquid at its melting point without changing temperature.
2. Latent Heat of Vaporisation
Heat required to convert a liquid into gas at its boiling point without changing temperature.
3. Kinetic Energy
Energy possessed by particles due to their motion.
4. Intermolecular Force
The force of attraction between particles of matter.
5. Condensation
Conversion of gas into liquid on cooling.
Related Practice Questions
- What is latent heat of fusion?
- Define latent heat of vaporisation.
- How does heat affect particle motion?
- Which state has the weakest intermolecular force?
- What is condensation?
Mini Quiz Challenge
Fill in the blanks
- Melting requires latent heat of __________.
- Water changes into steam by __________.
- Gas changes into liquid by __________.
Answers
- Fusion
- Vaporisation
- Condensation
Exam Tips
✔ Learn all state-change processes carefully.
✔ Revise latent heat definitions regularly.
✔ Remember the direction of state changes.
✔ Practice NCERT examples thoroughly.
✔ Understand particle behavior during heating and cooling.
Quick Revision Notes
✔ Fusion means melting.
✔ Vaporisation means liquid to gas conversion.
✔ Heating increases kinetic energy.
✔ Gases have the weakest intermolecular force.
✔ Condensation converts gas into liquid.
✔ Temperature remains constant during latent heat processes.
✔ State changes require energy transfer.
Common Mistakes Students Make
❌ Confusing fusion with vaporisation.
❌ Forgetting that temperature remains constant during melting.
❌ Mixing condensation with evaporation.
❌ Assuming particle size increases on heating.
❌ Confusing intermolecular force with kinetic energy.
Key Takeaways
✔ Latent heat changes the state of matter.
✔ Fusion converts solids into liquids.
✔ Vaporisation converts liquids into gases.
✔ Heating increases particle motion.
✔ Gases have very weak intermolecular forces.
✔ Condensation occurs when gases cool.
FAQs
1. What is latent heat of fusion?
Heat required to convert a solid into liquid without temperature change.
2. What is latent heat of vaporisation?
Heat required to convert a liquid into gas without temperature change.
3. What happens when matter is heated?
Particle motion and kinetic energy increase.
4. Which state has the weakest force of attraction?
Gaseous state.
5. What is condensation?
The conversion of gas into liquid.
Conclusion
Latent heat and changes of state explain how matter transforms under different conditions. Understanding fusion, vaporisation, condensation, and particle motion helps students build a strong foundation in chemistry and prepares them for future scientific studies.
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