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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 particle attraction, compressibility, evaporation, diffusion, and change of state 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: Moderate
Based On: NCERT Latest Syllabus (2026)
Introduction
Matter is made up of tiny particles that are continuously moving and attracting one another. The arrangement and behavior of these particles determine whether a substance exists as a solid, liquid, or gas. Understanding these concepts helps explain many everyday observations.
What You Will Learn
✔ Intermolecular forces
✔ Compressibility of matter
✔ Factors affecting evaporation
✔ Diffusion and particle motion
✔ State changes of matter
✔ NCERT-based concepts
✔ Practical applications
Why This Topic Is Important?
The concepts of particle attraction, diffusion, and evaporation form the basis of chemistry. Questions from these topics frequently appear in school examinations, Olympiads, scholarship tests, and competitive exams.
1. MCQ Questions with Detailed Solutions
Q1. Which of the following substances has the strongest force of attraction between its particles?
A) Oxygen Gas
B) Water
C) Iron
D) Steam
Answer
C) Iron
Concept Behind This Question
Solids have the strongest intermolecular forces.
Step-by-Step Solution
- Iron is a solid.
- Solid particles are tightly packed.
- They possess strong attractive forces.
Therefore, the correct answer is:
Iron
Exam Tip
The stronger the attraction, the more rigid the substance.
Q2. Why can gases be compressed easily?
A) Their particles are very large
B) They have large spaces between particles
C) Their particles stop moving
D) They have strong intermolecular forces
Answer
B) They have large spaces between particles
Concept Behind This Question
Compression is possible because gas particles are far apart.
Step-by-Step Solution
- Gas particles have maximum intermolecular space.
- These spaces can be reduced by applying pressure.
- Hence gases are highly compressible.
Exam Tip
LPG cylinders store compressed gas.
Q3. Which factor does NOT increase the rate of evaporation?
A) High temperature
B) Large surface area
C) High wind speed
D) High humidity
Answer
D) High humidity
Concept Behind This Question
Humidity slows down evaporation.
Step-by-Step Solution
- Humid air already contains water vapour.
- Fewer liquid particles can escape into the air.
- Therefore, evaporation decreases.
Exam Tip
Clothes take longer to dry during humid weather.
Q4. Which of the following is an example of diffusion in gases?
A) Sugar dissolving in water
B) Melting wax
C) Smell of cooking food spreading through the house
D) Freezing water
Answer
C) Smell of cooking food spreading through the house
Concept Behind This Question
Gas particles mix rapidly due to continuous motion.
Step-by-Step Solution
- Aroma particles move through air.
- They spread throughout the room automatically.
- This process is diffusion.
Exam Tip
Diffusion occurs fastest in gases.
Q5. What happens when ice absorbs heat continuously?
A) It becomes colder
B) It changes into water
C) It changes directly into steam
D) Its mass decreases
Answer
B) It changes into water
Concept Behind This Question
Heating causes a change of state from solid to liquid.
Step-by-Step Solution
- Ice absorbs heat energy.
- At 0°C, it melts into liquid water.
- This process is called melting.
Exam Tip
Melting is a solid-to-liquid state change.
Important Formulas & Concepts
1. Intermolecular Force
The force of attraction between particles of matter.
2. Compressibility
The ability of a substance to decrease its volume under pressure.
3. Evaporation
The conversion of liquid into vapour from its surface.
4. Diffusion
The spontaneous mixing of particles of substances.
5. Melting
The conversion of a solid into a liquid by heating.
Related Practice Questions
- Why do solids have strong intermolecular forces?
- Why are gases highly compressible?
- How does humidity affect evaporation?
- Give an example of diffusion in gases.
- What is melting?
Mini Quiz Challenge
Fill in the blanks
- Gases are highly __________.
- Humidity __________ evaporation.
- Ice changes into __________ on melting.
Answers
- Compressible
- Decreases
- Water
Exam Tips
✔ Learn the properties of all three states of matter.
✔ Revise factors affecting evaporation.
✔ Practice examples of diffusion.
✔ Understand state changes thoroughly.
✔ Focus on NCERT activities and observations.
Quick Revision Notes
✔ Solids have the strongest intermolecular force.
✔ Gases are highly compressible.
✔ High humidity reduces evaporation.
✔ Diffusion occurs fastest in gases.
✔ Ice melts into water at 0°C.
✔ Particle attraction varies in different states.
✔ Matter changes state by gaining or losing heat.
Common Mistakes Students Make
❌ Confusing melting with evaporation.
❌ Assuming humidity increases evaporation.
❌ Forgetting that gases have large intermolecular spaces.
❌ Mixing diffusion with dissolution.
❌ Ignoring the role of particle attraction.
Key Takeaways
✔ Solids have strong intermolecular forces.
✔ Gases can be compressed because of large spaces between particles.
✔ Humidity slows evaporation.
✔ Diffusion is fastest in gases.
✔ Melting converts solids into liquids.
✔ Understanding particle behavior helps explain state changes.
FAQs
1. Why are gases highly compressible?
Because there are large spaces between gas particles.
2. What is diffusion?
The spontaneous mixing of particles of substances.
3. How does humidity affect evaporation?
Humidity decreases the rate of evaporation.
4. What is melting?
The conversion of a solid into a liquid.
5. Which state has the strongest force of attraction?
The solid state.
Conclusion
The properties of matter are determined by the arrangement and attraction of particles. Concepts such as diffusion, evaporation, compressibility, and melting are essential for understanding both chemistry and everyday life.
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