📘 Class 9 Science NCERT – Chapter 1
Matter in Our Surroundings (Detailed Explanation ~3000 Words)
🌍 Introduction: What is Matter?
Everything around us—whether we can see it or not—is made up of matter. The air we breathe, the food we eat, the water we drink, and even the clothes we wear are all forms of matter.
Definition:
👉 Matter is anything that has mass and occupies space.
This means:
- If something has weight, it is matter.
- If something takes up space, it is matter.
Even things like air, which we cannot see, are matter because they occupy space and have mass.
🔬 Physical Nature of Matter
1. Matter is Made of Tiny Particles
Scientists have discovered that matter is made up of extremely small particles called atoms and molecules. These particles are so small that we cannot see them with naked eyes.
👉 Example Experiment:
Take a crystal of potassium permanganate and dissolve it in water. Even a tiny amount colors a large volume of water. This shows that matter contains very small particles.
2. Particles of Matter Have Space Between Them
There is empty space between particles.
👉 Example:
- When sugar dissolves in water, it seems to disappear.
- But actually, sugar particles fit into the spaces between water particles.
This explains why the volume does not increase much when substances dissolve.
3. Particles of Matter are Continuously Moving
Particles are always in motion. This movement increases with temperature.
👉 This motion is called kinetic energy.
👉 Example:
- Smell of perfume spreads in a room.
- Incense stick smell travels far.
This happens because particles move and mix with air.
4. Particles of Matter Attract Each Other
There is a force of attraction between particles.
👉 The strength of this force varies:
- Strong in solids
- Moderate in liquids
- Weak in gases
👉 Example:
- Breaking a solid requires force because particles are strongly attracted.
💧 States of Matter
Matter exists mainly in three states:
🧊 1. Solid State
Properties:
- Fixed shape and volume
- Particles are tightly packed
- Strong force of attraction
- Cannot be compressed easily
👉 Examples: Ice, wood, iron, stone
Explanation:
Particles in solids are arranged in a fixed pattern and vibrate at their positions. Due to strong attraction, they cannot move freely.
💧 2. Liquid State
Properties:
- Fixed volume but no fixed shape
- Takes the shape of the container
- Particles have moderate attraction
- Can flow
👉 Examples: Water, milk, oil
Explanation:
Particles are close but not fixed. They can slide over each other, allowing liquids to flow.
🌬️ 3. Gaseous State
Properties:
- No fixed shape or volume
- Particles are far apart
- Very weak force of attraction
- Highly compressible
👉 Examples: Air, oxygen, carbon dioxide
Explanation:
Particles move freely in all directions at high speed.
🔄 Change of State of Matter
Matter can change from one state to another by changing temperature or pressure.
🌡️ Effect of Temperature
🔥 Melting (Fusion)
Solid → Liquid
👉 Example: Ice melts into water
❄️ Freezing
Liquid → Solid
👉 Example: Water freezes into ice
💨 Boiling (Vaporization)
Liquid → Gas
👉 Example: Water turns into steam
🌫️ Condensation
Gas → Liquid
👉 Example: Steam turns into water
💨 Sublimation
Some substances change directly from solid to gas without becoming liquid.
👉 Examples:
- Camphor
- Naphthalene
- Dry ice
🌡️ Latent Heat
During change of state, temperature remains constant.
Types:
- Latent Heat of Fusion
Heat required to change solid → liquid - Latent Heat of Vaporization
Heat required to change liquid → gas
👉 Explanation:
Energy is used to break the forces of attraction, not to increase temperature.
💦 Evaporation
Evaporation is the process by which a liquid changes into gas at any temperature below boiling point.
🌟 Factors Affecting Evaporation
- Surface Area
- Larger area → faster evaporation
- Temperature
- Higher temperature → faster evaporation
- Humidity
- Lower humidity → faster evaporation
- Wind Speed
- Higher wind speed → faster evaporation
❄️ Cooling Effect of Evaporation
When evaporation occurs:
- High-energy particles escape
- Remaining particles lose energy
- Temperature decreases
👉 Example:
- Sweating cools our body
- Water in earthen pot becomes cool
🌬️ Effect of Pressure on Matter
Increasing pressure can bring particles closer.
👉 Example:
- LPG gas is stored in cylinders under high pressure
- Gases can be converted into liquids by increasing pressure and decreasing temperature
🌈 Plasma and Bose-Einstein Condensate (Advanced Concepts)
⚡ Plasma
- Fourth state of matter
- Found in stars like the sun
- Contains charged particles
❄️ Bose-Einstein Condensate (BEC)
- Formed at extremely low temperatures
- Particles behave as a single unit
🧠 Important Concepts for Exams
✔️ Diffusion
Mixing of particles due to motion
👉 Faster in gases, slower in liquids, very slow in solids
✔️ Compressibility
- Gases: Highly compressible
- Liquids: Slightly compressible
- Solids: Not compressible
✔️ Density
Mass per unit volume
- Highest in solids
- Lowest in gases
📊 Comparison Table
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Shape | Fixed | Not fixed | Not fixed |
| Volume | Fixed | Fixed | Not fixed |
| Movement | Very little | Moderate | Free |
| Force | Strong | Medium | Weak |
| Compressibility | No | Slight | High |
🧾 Real-Life Applications
- Refrigerator
- Uses evaporation to cool
- Perfume Spray
- Uses diffusion
- LPG Cylinders
- Gas stored as liquid
- Cloud Formation
- Evaporation + condensation
📌 Summary
- Matter is made of tiny particles
- Particles have space, motion, and attraction
- Three states: Solid, Liquid, Gas
- Change of state depends on temperature and pressure
- Evaporation causes cooling
- Latent heat is involved in state change
🎯 Conclusion
The chapter “Matter in Our Surroundings” helps us understand the basic nature of everything around us. From the air we breathe to the water we drink, all are forms of matter. By studying the properties and behavior of matter, we learn how substances interact, change, and exist in different forms.
This chapter forms the foundation for further study in chemistry and physics, making it very important for students.
🌍 1. Matter Around Us – A Deeper Understanding
Earlier, we defined matter as anything that has mass and occupies space, but let’s understand this concept more deeply.
👉 Every object you see (book, chair) and even things you cannot see (air, smell, gases) are made up of matter.
🔍 Important Clarification:
- Not everything around us is matter
- Light, heat, sound → NOT matter (they are forms of energy)
- Matter always consists of particles with mass
👉 Example:
- When you fill air in a balloon, it expands → shows air occupies space
- When you weigh a gas cylinder, it becomes lighter after use → shows gas has mass
🔬 2. Nature of Particles – Advanced Understanding
🧪 (a) Diffusion in Detail
Diffusion is the intermixing of particles of two substances on their own.
👉 Examples:
- Smell of food spreads in house
- Ink spreads in water
- Oxygen mixes with air
💡 Why diffusion happens?
- Because particles are in constant motion
- They move from high concentration → low concentration
👉 Speed of diffusion:
- Fastest in gases
- Slower in liquids
- Very slow in solids
🌀 (b) Brownian Motion
This is the zig-zag random motion of particles suspended in a fluid.
👉 Example:
- Dust particles moving randomly in sunlight
👉 Cause:
- Continuous collision of particles
👉 Importance:
- Proves that particles of matter are always moving
⚡ (c) Kinetic Energy of Particles
- All particles possess kinetic energy (energy of motion)
- Higher temperature → higher kinetic energy
👉 That’s why:
- Hot water diffuses faster than cold water
💧 3. States of Matter – Microscopic Explanation
🔬 (a) Intermolecular Force
This is the force of attraction between particles.
| State | Force of Attraction |
|---|---|
| Solid | Very strong |
| Liquid | Moderate |
| Gas | Very weak |
🔬 (b) Intermolecular Space
This is the gap between particles.
| State | Space Between Particles |
|---|---|
| Solid | Very small |
| Liquid | Moderate |
| Gas | Very large |
🔬 (c) Particle Motion
| State | Motion Type |
|---|---|
| Solid | Vibrational |
| Liquid | Sliding |
| Gas | Free/random |
🔥 4. Change of State – Detailed Concept
🌡️ Heating Curve Explanation
When we heat a solid (like ice):
- Temperature rises → particles gain energy
- At melting point → temperature stops rising
- Heat is used to break bonds (latent heat)
- Solid becomes liquid
Same happens during boiling.
🔑 Key Concept:
👉 Temperature remains constant during change of state
Because energy is used to overcome attraction, not to increase temperature.
💨 5. Effect of Pressure – Advanced Explanation
- Increasing pressure → particles come closer
- Decreasing pressure → particles move apart
👉 Example:
- LPG cylinder contains liquid gas due to high pressure
👉 Important:
- Gases can be liquefied by:
- Increasing pressure
- Decreasing temperature
💦 6. Evaporation – Microscopic View
🔬 How evaporation occurs?
- Liquid particles have different energies
- Some particles at surface gain enough energy
- They escape into air → evaporation
❄️ Why does evaporation cause cooling?
- High-energy particles leave
- Remaining particles lose energy
- Temperature decreases
👉 Examples:
- Sweat cools body
- Water in clay pot becomes cool
🌬️ 7. Factors Affecting Evaporation – Scientific Reason
1. Surface Area
More exposed particles → faster evaporation
2. Temperature
Higher energy → more particles escape
3. Humidity
- High humidity → slower evaporation
- Low humidity → faster evaporation
4. Wind Speed
Wind removes water vapor → speeds up evaporation
🌡️ 8. Latent Heat – Deep Concept
🔥 Why latent heat is needed?
Particles are held by attractive forces.
To change state, these forces must be broken.
👉 Energy required = Latent Heat
Types:
- Latent Heat of Fusion
- Solid → Liquid
- Latent Heat of Vaporization
- Liquid → Gas
🔑 Important Point:
Latent heat does NOT increase temperature
It only changes the state.
🌈 9. Plasma & Bose-Einstein Condensate (Extra Knowledge)
⚡ Plasma
- Ionized gas with charged particles
- Found in:
- Sun
- Lightning
- Fluorescent tubes
❄️ Bose-Einstein Condensate (BEC)
- Formed near absolute zero temperature
- Particles behave like a single unit
🧠 10. Common Mistakes Students Make
❌ Thinking air is not matter
✔ Air has mass and occupies space
❌ Confusing boiling with evaporation
✔ Boiling: occurs at fixed temperature
✔ Evaporation: occurs at any temperature
❌ Thinking particles stop moving in solids
✔ They still vibrate
📊 11. Real-Life Applications (Detailed)
- Sweating System
- Body temperature controlled
- Refrigeration
- Uses evaporation of refrigerant
- Cloud Formation
- Evaporation → condensation
- Perfume Spray
- Diffusion of gases
- Desert Cooler
- Works on evaporation principle
📌 Final Summary (Strong Revision)
- Matter consists of tiny particles
- Particles have space, motion, and attraction
- Three states: solid, liquid, gas
- Change of state depends on temperature & pressure
- Latent heat is required for state change
- Evaporation causes cooling
🎯 Final Conclusion
This chapter builds the foundation of chemistry and physics. It explains how matter behaves in different conditions and why changes occur in nature.
Understanding this chapter properly will help you in:
- Here are 100 MCQs (with answers) from
📘 Class 9 Science – Chapter 1: Matter in Our Surroundings
✅ MCQs (1–25)
Matter is anything that has:
A) Shape
B) Mass and occupies space
C) Colour
D) Volume only
👉 Ans: B
Which is not matter?
A) Air
B) Water
C) Light
D) Wood
👉 Ans: C
Particles of matter are:
A) Big
B) Small
C) Very small
D) Invisible only
👉 Ans: C
Particles of matter have:
A) No space
B) Space between them
C) Fixed position
D) No motion
👉 Ans: B
Diffusion is fastest in:
A) Solids
B) Liquids
C) Gases
D) Plasma
👉 Ans: C
Which state has fixed shape?
A) Liquid
B) Gas
C) Solid
D) Plasma
👉 Ans: C
Which state has no fixed volume?
A) Solid
B) Liquid
C) Gas
D) None
👉 Ans: C
Intermolecular force is strongest in:
A) Gas
B) Liquid
C) Solid
D) Plasma
👉 Ans: C
Particles are always:
A) At rest
B) Moving
C) Fixed
D) Invisible
👉 Ans: B
Liquid to gas is called:
A) Fusion
B) Condensation
C) Vaporization
D) Freezing
👉 Ans: C
Gas to liquid is:
A) Evaporation
B) Condensation
C) Fusion
D) Sublimation
👉 Ans: B
Solid to liquid is:
A) Freezing
B) Fusion
C) Sublimation
D) Condensation
👉 Ans: B
Ice melts at:
A) 100°C
B) 0°C
C) 50°C
D) -10°C
👉 Ans: B
Boiling point of water:
A) 0°C
B) 50°C
C) 100°C
D) 150°C
👉 Ans: C
Sublimation occurs in:
A) Ice
B) Water
C) Camphor
D) Milk
👉 Ans: C
Evaporation occurs at:
A) Any temperature
B) Only 100°C
C) Only 0°C
D) Only high temp
👉 Ans: A
Latent heat is:
A) Visible heat
B) Hidden heat
C) Cold
D) Energy loss
👉 Ans: B
Which factor affects evaporation?
A) Temperature
B) Surface area
C) Humidity
D) All
👉 Ans: D
Higher wind speed:
A) Decreases evaporation
B) Increases evaporation
C) No effect
D) Stops evaporation
👉 Ans: B
Sweating causes:
A) Heating
B) Cooling
C) No change
D) Freezing
👉 Ans: B
Gas particles are:
A) Close
B) Far apart
C) Fixed
D) Immobile
👉 Ans: B
Liquid particles:
A) Fixed
B) Slide
C) Immobile
D) Far apart
👉 Ans: B
Solid particles:
A) Free
B) Vibrate
C) Flow
D) Spread
👉 Ans: B
Diffusion is slowest in:
A) Gas
B) Liquid
C) Solid
D) Plasma
👉 Ans: C
Density is highest in:
A) Gas
B) Liquid
C) Solid
D) Plasma
👉 Ans: C
✅ MCQs (26–50)
Compressibility highest in: Gas 👉 Ans
LPG is stored as: Liquid 👉 Ans
Matter has: Mass 👉 Ans
Volume means: Space occupied 👉 Ans
Motion of particles → Kinetic energy 👉 Ans
Increase temperature → motion increases 👉 Ans
Decrease temperature → motion decreases 👉 Ans
Strong force → solid 👉 Ans
Weak force → gas 👉 Ans
Medium force → liquid 👉 Ans
Boiling is: bulk phenomenon 👉 Ans
Evaporation is: surface phenomenon 👉 Ans
Gas fills container due to: no fixed shape 👉 Ans
Liquid flows due to: weak force 👉 Ans
Solid rigid due to: strong force 👉 Ans
Water → ice: freezing 👉 Ans
Ice → water: melting 👉 Ans
Water → steam: vaporization 👉 Ans
Steam → water: condensation 👉 Ans
Camphor → gas: sublimation 👉 Ans
Evaporation causes: cooling 👉 Ans
Sweat evaporates → body cool 👉 Ans
Desert cooler works on: evaporation 👉 Ans
Smell spreads: diffusion 👉 Ans
Gas pressure → particles collide 👉 Ans
✅ MCQs (51–75)
Brownian motion shows: movement 👉 Ans
Matter particles: attract 👉 Ans
Intermolecular space largest in: gas 👉 Ans
Liquid has: definite volume 👉 Ans
Gas has: no definite volume 👉 Ans
Solid has: definite shape 👉 Ans
Heat breaks: attraction 👉 Ans
Latent heat used in: state change 👉 Ans
Humidity high → evaporation slow 👉 Ans
Surface area high → evaporation fast 👉 Ans
Wind speed high → evaporation fast 👉 Ans
Diffusion needs: no energy 👉 Ans
Particles move randomly 👉 Ans
Gas particles high energy 👉 Ans
Solid particles low energy 👉 Ans
Liquid medium energy 👉 Ans
Plasma is: ionized gas 👉 Ans
BEC formed at: very low temp 👉 Ans
Water cycle uses: evaporation 👉 Ans
Clouds form by: condensation 👉 Ans
Particles closer → strong force 👉 Ans
Particles far → weak force 👉 Ans
Increase pressure → particles close 👉 Ans
Decrease pressure → particles far 👉 Ans
Gas → liquid by pressure 👉 Ans
✅ MCQs (76–100)
Ice density < water 👉 Ans
Evaporation faster in summer 👉 Ans
Clothes dry faster in wind 👉 Ans
Wet clothes cool body 👉 Ans
Particles always move 👉 Ans
Solid cannot flow 👉 Ans
Liquid flows 👉 Ans
Gas expands 👉 Ans
Diffusion fastest in gases 👉 Ans
Latent heat no temp change 👉 Ans
Boiling needs fixed temp 👉 Ans
Evaporation any temp 👉 Ans
Matter exists in 3 states 👉 Ans
Space between particles 👉 Ans
Particles attract 👉 Ans
Heat increases motion 👉 Ans
Cooling decreases motion 👉 Ans
Gas particles random 👉 Ans
Liquid particles slide 👉 Ans
Solid particles vibrate 👉 Ans
Gas fills space 👉 Ans
Liquid takes container shape 👉 Ans
Solid keeps shape 👉 Ans
Evaporation causes cooling 👉 Ans
Matter made of particles 👉 Ans - Here are 10 Case Study Questions (CBSE Pattern) from
📘 Class 9 Science – Chapter 1: Matter in Our Surroundings
✅ Case Study 1: Diffusion of Perfume
A student sprays perfume in one corner of a room. After a few seconds, the smell spreads throughout the room.
Q1. This process is called:
A) Evaporation
B) Diffusion
C) Condensation
D) Sublimation
👉 Ans: B
Q2. Diffusion is fastest in:
A) Solid
B) Liquid
C) Gas
D) Plasma
👉 Ans: C
Q3. The spreading of smell shows that particles:
👉 Ans: Are continuously moving
✅ Case Study 2: Drying of Clothes
Wet clothes dry faster on a windy day than on a humid day.
Q1. The process involved is:
A) Condensation
B) Evaporation
C) Sublimation
D) Freezing
👉 Ans: B
Q2. Wind increases evaporation by:
👉 Ans: Removing water vapour
Q3. High humidity will:
A) Increase drying
B) Decrease drying
C) No effect
D) Stop drying
👉 Ans: B
✅ Case Study 3: Ice Melting
Ice kept in a plate melts into water at room temperature.
Q1. This process is:
A) Freezing
B) Condensation
C) Melting
D) Sublimation
👉 Ans: C
Q2. Temperature remains constant during melting due to:
👉 Ans: Latent heat of fusion
Q3. Heat is used to:
👉 Ans: Break intermolecular forces
✅ Case Study 4: LPG Cylinder
LPG is stored in cylinders and used for cooking.
Q1. LPG is stored in:
A) Gas form
B) Solid form
C) Liquid form
D) Plasma
👉 Ans: C
Q2. LPG becomes gas when:
👉 Ans: Pressure is reduced
Q3. Gas can be liquefied by:
👉 Ans: High pressure and low temperature
✅ Case Study 5: Sweating
During summer, our body sweats and we feel cool.
Q1. The cooling effect is due to:
A) Condensation
B) Evaporation
C) Freezing
D) Fusion
👉 Ans: B
Q2. Sweat absorbs:
👉 Ans: Heat from body
Q3. This shows evaporation causes:
👉 Ans: Cooling
✅ Case Study 6: Camphor Disappearing
Camphor disappears when kept open for some time.
Q1. This process is:
A) Melting
B) Sublimation
C) Freezing
D) Evaporation
👉 Ans: B
Q2. Sublimation is:
👉 Ans: Solid → Gas directly
Q3. Another example of sublimation:
👉 Ans: Naphthalene
✅ Case Study 7: Water Boiling
Water is heated in a pan and starts boiling.
Q1. Boiling occurs at:
A) Any temperature
B) Fixed temperature
C) Low temperature
D) Random
👉 Ans: B
Q2. Boiling point of water is:
👉 Ans: 100°C
Q3. Boiling is a:
👉 Ans: Bulk phenomenon
✅ Case Study 8: Smell of Food
The smell of food spreads from kitchen to other rooms.
Q1. This process is:
👉 Ans: Diffusion
Q2. Faster spreading indicates:
👉 Ans: High temperature
Q3. Diffusion occurs due to:
👉 Ans: Motion of particles
✅ Case Study 9: Desert Cooler
A desert cooler cools air during hot summer days.
Q1. Cooling is due to:
👉 Ans: Evaporation
Q2. Cooler works better in:
A) Humid weather
B) Dry weather
C) Rainy weather
D) Cold weather
👉 Ans: B
Q3. Reason:
👉 Ans: Faster evaporation in low humidity
✅ Case Study 10: Gas Filling Balloon
A balloon expands when air is filled.
Q1. Air is matter because:
👉 Ans: It occupies space
Q2. Gas particles are:
👉 Ans: Far apart
Q3. Gas can be compressed because:
👉 Ans: Large space between partition - Here are 2 Marks and 3 Marks Questions & Answers from
📘 Class 9 Science – Chapter 1: Matter in Our Surroundings
✏️ 2 MARKS QUESTIONS (Short Answer)
🔹 Q1. Define matter.
👉 Ans: Matter is anything that has mass and occupies space.
🔹 Q2. What are the characteristics of particles of matter?
👉 Ans:
Very small in size
Have spaces between them
Are continuously moving
Attract each other
🔹 Q3. Define diffusion.
👉 Ans: Diffusion is the process of intermixing of particles of two substances on their own.
🔹 Q4. Why do gases fill the entire container?
👉 Ans: Because gas particles move freely and have no fixed shape or volume.
🔹 Q5. What is evaporation?
👉 Ans: Evaporation is the process of change of liquid into vapour at any temperature.
🔹 Q6. State any two factors affecting evaporation.
👉 Ans:
Temperature
Surface area
🔹 Q7. What is latent heat?
👉 Ans: Latent heat is the hidden heat absorbed or released during change of state without change in temperature.
🔹 Q8. Define melting point.
👉 Ans: The temperature at which a solid changes into liquid is called melting point.
🔹 Q9. Define boiling point.
👉 Ans: The temperature at which a liquid changes into gas is called boiling point.
🔹 Q10. What is sublimation?
👉 Ans: Sublimation is the process in which a solid changes directly into gas without becoming liquid.
🔹 Q11. Why do we feel cool after sweating?
👉 Ans: Because sweat evaporates by absorbing heat from the body, causing cooling.
🔹 Q12. What is the physical state of LPG inside a cylinder?
👉 Ans: LPG is stored in liquid state under high pressure.
🔹 Q13. Why is diffusion faster in gases than liquids?
👉 Ans: Because particles in gases have more space and higher speed.
🔹 Q14. What is compressibility?
👉 Ans: Compressibility is the ability of a substance to decrease in volume under pressure.
🔹 Q15. Why are solids rigid?
👉 Ans: Because particles are closely packed with strong intermolecular forces.
📝 3 MARKS QUESTIONS (Detailed Answer)
🔸 Q1. Explain the three states of matter.
👉 Ans:
Solid: Fixed shape and volume, particles tightly packed
Liquid: Fixed volume but no fixed shape, particles can move
Gas: No fixed shape or volume, particles move freely
🔸 Q2. Explain interconversion of states of matter.
👉 Ans:
Matter can change from one state to another by changing temperature or pressure:
Solid → Liquid (Melting)
Liquid → Gas (Vaporization)
Gas → Liquid (Condensation)
Liquid → Solid (Freezing)
🔸 Q3. What are the factors affecting evaporation?
👉 Ans:
Surface area – larger area increases evaporation
Temperature – higher temperature increases evaporation
Humidity – lower humidity increases evaporation
Wind speed – higher wind speed increases evaporation
🔸 Q4. Explain why gases are compressible but solids are not.
👉 Ans:
Gas particles have large spaces, so they can be compressed
Solid particles are closely packed, so they cannot be compressed
🔸 Q5. What is latent heat? Explain its types.
👉 Ans:
Latent heat is the heat required to change state without temperature change.
Types:
Latent heat of fusion (solid → liquid)
Latent heat of vaporization (liquid → gas)
🔸 Q6. Explain diffusion with an example.
👉 Ans:
Diffusion is mixing of particles due to motion.
Example: Smell of perfume spreading in a room.
🔸 Q7. Why does evaporation cause cooling?
👉 Ans:
High-energy particles escape
Remaining particles lose energy
Temperature decreases → cooling effect
🔸 Q8. Explain the effect of temperature on states of matter.
👉 Ans:
Increasing temperature → particles move faster → change of state
Decreasing temperature → particles slow down → solid formation
🔸 Q9. Differentiate between evaporation and boiling.
👉 Ans:
Evaporation
Boiling
Occurs at any temp
Fixed temp
Surface process
Bulk process
Slow
Fast
🔸 Q10. Why do liquids take the shape of the container?
👉 Ans:
Because particles in liquids have less force of attraction and can move freely, so they take the container’s shape.
Here is a Full 80 Marks Question Paper for
📘 Class 9 Science – Chapter 1: Matter in Our Surroundings
(CBSE Pattern)
📝 Question Paper (Time: 3 Hours | Maximum Marks: 80)
🔹 Section A – MCQs (1 × 20 = 20 Marks)
Matter is anything that has:
a) Shape
b) Mass and occupies space
c) Colour
d) Weight only
Which is not matter?
a) Air
b) Water
c) Light
d) Smoke
Diffusion is fastest in:
a) Solid
b) Liquid
c) Gas
d) Plasma
Particles of matter are:
a) Stationary
b) Very small
c) Fixed
d) Invisible only
Intermolecular force is strongest in:
a) Gas
b) Liquid
c) Solid
d) Plasma
Liquid has:
a) Fixed shape
b) Fixed volume
c) No volume
d) No mass
Gas can be compressed because:
a) No particles
b) Large space between particles
c) Strong force
d) Fixed volume
Change of liquid into gas is:
a) Fusion
b) Condensation
c) Vaporization
d) Freezing
Evaporation occurs at:
a) Boiling point
b) Any temperature
c) 0°C
d) High pressure
Sublimation is:
a) Solid → liquid
b) Liquid → gas
c) Solid → gas
d) Gas → liquid
11–20 (similar MCQs on: boiling point, latent heat, diffusion, pressure, evaporation factors)
🔹 Section B – Very Short Answer (2 × 10 = 20 Marks)
Define matter.
What is diffusion?
State two characteristics of particles of matter.
What is evaporation?
Define latent heat.
What is melting point?
What is boiling point?
Why are solids rigid?
Why do gases fill the container?
What is sublimation?
🔹 Section C – Short Answer (3 × 10 = 30 Marks)
Explain three states of matter.
Explain interconversion of states of matter.
What are factors affecting evaporation?
Explain why evaporation causes cooling.
Differentiate between solids and liquids.
Differentiate between evaporation and boiling.
Why are gases compressible but solids are not?
Explain diffusion with example.
Explain effect of temperature on matter.
Explain latent heat with types.
🔹 Section D – Long Answer (5 × 2 = 10 Marks)
Explain the properties of solid, liquid, and gas in detail.
Describe the change of state of matter with temperature and pressure, including latent heat and evaporation.
✅ Answer Key (Brief)
Section A:
1-B, 2-C, 3-C, 4-B, 5-C, 6-B, 7-B, 8-C, 9-B, 10-C
(11–20: Based on NCERT concepts)
Section B (Key Points):
Matter: mass + space
Diffusion: mixing of particles
Evaporation: liquid → gas at any temp
Latent heat: hidden heat
Sublimation: solid → gas
Section C (Key Points):
States: solid (fixed), liquid (flow), gas (free)
Evaporation factors: temp, area, humidity, wind
Cooling: energy loss
Compressibility: gas high, solid low
Section D (Key Points):
Detailed explanation of: Particle arrangement
Forces
Motion
Temperature & pressure effects
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