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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 conceptual MCQs on temperature, pressure, state changes, latent heat, and molecular motion 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 changes its state when temperature or pressure changes. These changes occur because particles gain or lose energy, affecting their movement and the forces between them. Understanding these concepts is essential for mastering the fundamentals of chemistry.
What You Will Learn
✔ Effect of pressure on matter
✔ State changes
✔ Latent heat applications
✔ Particle movement
✔ Molecular behavior
✔ NCERT-based concepts
✔ Real-life observations
Why This Topic Is Important?
Questions based on pressure, temperature, and state changes are commonly asked in examinations. These concepts also help explain several natural and industrial processes.
1. MCQ Questions with Detailed Solutions
Q1. Which factor can change a gas into a liquid without changing its chemical composition?
A) Increasing pressure
B) Decreasing pressure
C) Adding salt
D) Stirring continuously
Answer
A) Increasing pressure
Concept Behind This Question
Gas particles can be brought closer together by applying pressure.
Step-by-Step Solution
- Gas particles are far apart.
- Increasing pressure reduces the distance between particles.
- Under suitable conditions, gas converts into liquid.
Therefore, the correct answer is:
Increasing pressure
Exam Tip
Both high pressure and low temperature help liquefy gases.
Q2. Which of the following has the maximum kinetic energy?
A) Ice at 0°C
B) Water at 25°C
C) Steam at 100°C
D) Ice at -10°C
Answer
C) Steam at 100°C
Concept Behind This Question
Gas particles possess higher kinetic energy than liquid and solid particles.
Step-by-Step Solution
- Steam is in the gaseous state.
- Gas particles move more freely and rapidly.
- Therefore, steam has the highest kinetic energy.
Exam Tip
Gas > Liquid > Solid in particle kinetic energy.
Q3. Why does a desert cooler work better on a hot dry day?
A) Humidity is high
B) Evaporation occurs more rapidly
C) Air pressure is lower
D) Water becomes colder automatically
Answer
B) Evaporation occurs more rapidly
Concept Behind This Question
Low humidity increases evaporation.
Step-by-Step Solution
- Dry air contains less water vapour.
- Water evaporates faster.
- Faster evaporation produces greater cooling.
Exam Tip
Coolers are less effective during humid weather.
Q4. During the boiling of water, the heat supplied is mainly used for:
A) Increasing temperature
B) Breaking intermolecular attractions
C) Increasing mass
D) Changing colour
Answer
B) Breaking intermolecular attractions
Concept Behind This Question
Latent heat is used to overcome forces between particles.
Step-by-Step Solution
- At the boiling point, temperature remains constant.
- Heat energy separates particles further apart.
- This allows water to change into steam.
Exam Tip
Boiling involves latent heat of vaporisation.
Q5. Which state of matter has the highest rate of diffusion?
A) Solid
B) Liquid
C) Gas
D) All are equal
Answer
C) Gas
Concept Behind This Question
Gas particles move with maximum freedom.
Step-by-Step Solution
- Gas particles move rapidly in all directions.
- Mixing occurs much faster than in liquids or solids.
- Therefore, gases diffuse most rapidly.
Exam Tip
Remember: Diffusion Rate → Gas > Liquid > Solid.
Important Formulas & Concepts
1. Liquefaction of Gas
Conversion of gas into liquid by increasing pressure and lowering temperature.
2. Latent Heat of Vaporisation
Heat required to convert liquid into gas without changing temperature.
3. Kinetic Energy
Energy possessed by moving particles.
4. Diffusion Rate
Gas > Liquid > Solid
5. Evaporative Cooling
Cooling produced due to evaporation.
Related Practice Questions
- How can gases be liquefied?
- Which state has maximum kinetic energy?
- Why do desert coolers work effectively?
- What is latent heat of vaporisation?
- Which state diffuses fastest?
Mini Quiz Challenge
Fill in the blanks
- Gas can be converted into liquid by increasing __________.
- Steam possesses high __________ energy.
- Diffusion is fastest in __________.
Answers
- Pressure
- Kinetic
- Gases
Exam Tips
✔ Understand the role of pressure in state changes.
✔ Revise latent heat concepts carefully.
✔ Learn practical applications of evaporation.
✔ Compare particle motion in all states.
✔ Practice conceptual NCERT questions.
Quick Revision Notes
✔ Gases can be liquefied by pressure and cooling.
✔ Steam has higher kinetic energy than water.
✔ Desert coolers work better in dry weather.
✔ Boiling uses latent heat of vaporisation.
✔ Diffusion is fastest in gases.
✔ Gas particles move very rapidly.
✔ State changes depend on temperature and pressure.
Common Mistakes Students Make
❌ Confusing evaporation with boiling.
❌ Forgetting the role of pressure in liquefaction.
❌ Assuming temperature rises during boiling.
❌ Ignoring humidity effects.
❌ Mixing kinetic energy with latent heat.
Key Takeaways
✔ Pressure helps convert gases into liquids.
✔ Gas particles possess maximum kinetic energy.
✔ Dry weather increases evaporation.
✔ Latent heat breaks intermolecular attractions.
✔ Diffusion occurs fastest in gases.
✔ State changes depend on particle behavior.
FAQs
1. How can a gas be converted into a liquid?
By increasing pressure and lowering temperature.
2. Which state has maximum kinetic energy?
The gaseous state.
3. Why do desert coolers work better in dry weather?
Because evaporation occurs faster.
4. What happens during boiling?
Heat is used to overcome intermolecular forces.
5. Which state diffuses fastest?
The gaseous state.
Conclusion
The behavior of matter depends on particle motion, temperature, and pressure. Concepts such as liquefaction, latent heat, diffusion, and evaporation explain many real-life phenomena and strengthen students’ understanding of chemistry.
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