Important Questions Class 8 Science Chapter 7: Particulate Nature of Matter

Matter is anything that has mass and occupies space.
The physical state of matter depends on particle arrangement, interparticle spaces and interparticle attraction.

Matter exists as solids, liquids and gases because its particles are arranged differently in each state. Important Questions Class 8 Science Chapter 7 help students practise constituent particles, interparticle spaces, interparticle attraction, solids, liquids, gases, melting point, boiling point, evaporation, compressibility, diffusion, movement of particles, and particulate nature of matter. The CBSE 2026 chapter explains these ideas through chalk powder, sugar solution, water in containers, smoke in gas jars, syringe compression, potassium permanganate and incense stick fragrance.

Key Takeaways

• Matter: Matter is made of extremely small particles that cannot be seen through an ordinary microscope.
• Solids: Solids have fixed shape and volume due to strong interparticle attraction.
• Liquids: Liquids have fixed volume but no fixed shape because particles can move within limited space.
• Gases: Gases have no fixed shape or volume because particles move freely in all available space.

Important Questions Class 8 Science Chapter 7 Structure 2026

Important Questions Class 8 Science Chapter 7 with Answers

Particulate Nature of Matter explains how tiny particles form solids, liquids and gases.
Students should connect every answer with particle spacing, attraction, movement or thermal energy.
These particulate nature of matter class 8 questions follow the NCERT 2026 chapter flow.

1. What does Important Questions Class 8 Science Chapter 7 mainly teach?

Important Questions Class 8 Science Chapter 7 mainly teach constituent particles, interparticle spaces, interparticle attraction, states of matter, melting, boiling, evaporation, compressibility and diffusion. The chapter connects visible properties with invisible particles.

1. Particle Skill: Explain that matter is made of particles.
2. State Skill: Compare solids, liquids and gases.
3. Heat Skill: Explain melting and boiling.
4. Movement Skill: Explain diffusion and spreading.
5. Final Result: Chapter 7 teaches matter through particle behaviour.

2. What is the name of Class 8 Science Chapter 7?

The name of Class 8 Science Chapter 7 is Particulate Nature of Matter. It explains matter through extremely small particles.

1. Chapter Number: 7.
2. Chapter Name: Particulate Nature of Matter.
3. Textbook: Curiosity.
4. Final Result: Chapter 7 studies particles of matter.

3. Why does the chapter begin with pebbles, stones and sand?

The chapter begins with pebbles, stones and sand to show how large rocks break into smaller pieces. It then asks whether these pieces can break further.

1. Rocks: Break due to erosion.
2. Rivers: Carry rock pieces.
3. Result: Pebbles, stones, sand and clay form.
4. Final Result: Rocks break into smaller particles over time.

Class 8 Science Chapter 7 Important Questions

Class 8 Science Chapter 7 important questions focus on the particle model of matter.
The chapter shows that visible materials have invisible building blocks.
Students should explain observations through particles rather than only visible changes.

4. What is matter composed of?

Matter is composed of a large number of extremely small particles. These particles form all substances and materials.

1. Substance: Chalk, sugar, water or air.
2. Basic Idea: Each contains tiny particles.
3. Visibility: Particles are too small for ordinary microscopes.
4. Final Result: Matter is made up of extremely small particles.

5. What are constituent particles?

Constituent particles are the basic units that make up a larger piece of a substance or material. Chalk is made of constituent particles of chalk.

1. Object: Chalk stick.
2. Breaking: Gives smaller chalk pieces.
3. Grinding: Gives fine chalk powder.
4. Final Result: Constituent particles form larger substances.

6. What does grinding chalk show about matter?

Grinding chalk shows that a large piece of matter contains many smaller units. The chalk remains chalk after grinding.

1. Action: Break and grind chalk.
2. Change: Size reduces.
3. Substance: Chalk does not become new material.
4. Final Result: Grinding chalk is a physical change.

7. Why is grinding chalk a physical change?

Grinding chalk is a physical change because only size changes. No new substance forms during grinding.

1. Before Grinding: Chalk.
2. After Grinding: Chalk powder.
3. Chemical Change: Not observed.
4. Final Result: Grinding changes size, not substance.

8. Can chalk powder be broken further?

Yes, chalk powder can be imagined as broken further into smaller particles. Eventually, it reaches constituent particles.

1. First Stage: Chalk stick.
2. Second Stage: Chalk pieces.
3. Third Stage: Fine powder.
4. Final Result: Matter can be divided into very small particles.

Matter is Made Up of Particles Class 8 Questions

Matter is made up of particles class 8 questions explain invisible particle evidence.
Sugar solution and chalk powder show that matter has tiny units.
The chapter uses these activities to build the particulate model.

9. What happens when sugar dissolves in water?

Sugar breaks into tiny constituent particles and spreads through water. It becomes invisible but can still be tasted.

1. Sugar: Added to water.
2. Stirring: Helps dissolution.
3. Taste: Water becomes sweet.
4. Final Result: Sugar particles spread in water.

10. Where does sugar go after dissolving in water?

Sugar occupies the spaces between water particles after dissolving. Its particles spread throughout the solution.

1. Water: Contains interparticle spaces.
2. Sugar: Breaks into tiny particles.
3. Solution: Tastes sweet throughout.
4. Final Result: Sugar particles enter spaces between water particles.

11. Why can dissolved sugar not be seen?

Dissolved sugar cannot be seen because it breaks into extremely tiny particles. These particles are too small for naked-eye observation.

1. Before Dissolving: Sugar grains are visible.
2. After Dissolving: Particles separate.
3. Observation: Sweet taste remains.
4. Final Result: Invisible sugar particles remain in solution.

12. How does sugar solution prove that matter has particles?

Sugar solution proves it because sugar becomes invisible but remains present. Its particles spread between water particles.

1. Evidence: Sweet taste.
2. No Visible Grains: Sugar disappears.
3. Conclusion: Tiny particles exist.
4. Final Result: Dissolution supports particulate nature of matter.

13. Why is ocean water salty even when salt is not visible?

Ocean water is salty because salt particles are dissolved in it. The particles are too small to see but can be tasted.

1. Salt: Present in dissolved form.
2. Visibility: Not seen as grains.
3. Taste: Salty.
4. Final Result: Dissolved salt particles make ocean water salty.

Constituent Particles Class 8 Questions

Constituent particles class 8 questions help students understand the smallest units of substances.
These particles are much smaller than dust, sand grains or chalk powder.
The chapter later links these particles with atoms and molecules.

14. Are grains of sand the smallest units of rock?

No, grains of sand are not the smallest units of rock. They are made of many constituent particles.

1. Rock: Breaks into pieces.
2. Sand Grain: Still contains particles.
3. Further Division: Possible in theory.
4. Final Result: Sand grains are not the smallest units.

15. Are dust particles the same as constituent particles of matter?

No, dust particles are not the same as constituent particles of matter. Dust particles are much larger and are also made of constituent particles.

1. Dust Particle: Tiny but visible in some conditions.
2. Constituent Particle: Extremely smaller.
3. Example: Suspended particulate matter differs from atoms and molecules.
4. Final Result: Dust particles contain many constituent particles.

16. What did Acharya Kanad propose about matter?

Acharya Kanad proposed that matter is made of tiny indivisible eternal particles called Parmanu. His idea appears in Vaisheshika Sutras.

1. Thinker: Acharya Kanad.
2. Concept: Parmanu.
3. Text: Vaisheshika Sutras.
4. Final Result: Ancient Indian thought included atom-like particles.

17. What are atoms and molecules in simple terms?

Atoms and molecules are tiny particles that make up matter. Iron contains iron atoms, while water contains water molecules.

1. Iron: Made of iron atoms.
2. Hydrogen: Forms hydrogen molecules.
3. Water: Has hydrogen and oxygen atoms.
4. Final Result: Atoms and molecules are particles of matter.

Interparticle Spaces Class 8 Questions

Interparticle spaces class 8 questions explain why substances can mix and dissolve.
Spaces exist between particles of matter.
Dissolved particles can occupy these spaces.

18. What are interparticle spaces?

Interparticle spaces are the spaces present between particles of matter. Dissolved sugar can occupy spaces between water particles.

1. Water: Has spaces between particles.
2. Sugar: Enters these spaces.
3. Solution: Volume may not increase as expected.
4. Final Result: Interparticle spaces exist between particles.

19. How does dissolving sugar prove interparticle spaces?

Dissolving sugar proves interparticle spaces because sugar particles occupy spaces between water particles. The total volume does not simply equal water plus sugar volume.

1. Initial Water Level: Marked as A.
2. After Sugar Addition: Level rises.
3. After Dissolving: Level may decrease.
4. Final Result: Sugar particles fit into spaces between water particles.

20. Why does sand not dissolve in water like sugar?

Sand does not dissolve because water particles cannot pull out its constituent particles. Sand particles settle down instead.

1. Sugar: Dissolves in water.
2. Sand: Does not dissolve.
3. Observation: Sand settles at the bottom.
4. Final Result: Sand is insoluble in water.

21. Why does adding sand increase water volume?

Adding sand increases water volume because sand particles do not dissolve. They occupy extra space in the container.

1. Sand: Insoluble solid.
2. Water: Does not separate sand particles.
3. Level: Total volume increases.
4. Final Result: Undissolved sand occupies visible space.

22. Do particles in solids have spaces between them?

Yes, particles in solids have some spaces between them. These spaces are very small compared with liquids and gases.

1. Solid Particles: Closely packed.
2. Spaces: Very small.
3. Common Mistake: Spaces are not filled with air.
4. Final Result: Solids also have tiny interparticle spaces.

Interparticle Attraction Class 8 Questions

Interparticle attraction class 8 questions explain why matter stays together.
Particles attract each other, and this attraction differs in solids, liquids and gases.
The strength of attraction depends on particle distance and substance type.

23. What is interparticle attraction?

Interparticle attraction is the attractive force that holds particles of matter together. It decides many physical properties.

1. Particles: Attract one another.
2. Distance: Affects force strength.
3. State: Strong attraction gives solid-like behaviour.
4. Final Result: Interparticle attraction holds matter together.

24. How does interparticle distance affect attraction?

Interparticle attraction decreases when distance between particles increases. Even a slight increase can weaken attraction greatly.

1. Small Distance: Strong attraction.
2. Large Distance: Weak attraction.
3. Gas Particles: Attraction is negligible.
4. Final Result: Greater distance weakens interparticle attraction.

25. In which state is interparticle attraction strongest?

Interparticle attraction is strongest in solids. This keeps particles in fixed positions.

1. Solid: Strongest attraction.
2. Liquid: Weaker attraction.
3. Gas: Negligible attraction.
4. Final Result: Solids have maximum interparticle attraction.

26. In which state is interparticle attraction weakest?

Interparticle attraction is weakest in gases. Gas particles move freely in all directions.

1. Gas: Maximum spacing.
2. Attraction: Negligible.
3. Motion: Free movement.
4. Final Result: Gases have minimum interparticle attraction.

27. What decides the physical state of a substance?

The physical state depends on interparticle attraction, interparticle distance and particle thermal energy. These factors decide solid, liquid or gas state.

1. Attraction: Holds particles together.
2. Spacing: Decides packing.
3. Thermal Energy: Affects movement.
4. Final Result: Particle behaviour decides state of matter.

States of Matter Class 8 Questions

States of matter class 8 questions compare solids, liquids and gases.
The chapter explains them through particle spacing, attraction and movement.
Each state has a distinct shape and volume behaviour.

28. What are the three common states of matter?

The three common states of matter are solid, liquid and gas. Their particles differ in spacing, movement and attraction.

1. Solid: Fixed shape and volume.
2. Liquid: Fixed volume but no fixed shape.
3. Gas: No fixed shape or volume.
4. Final Result: Matter commonly exists as solid, liquid or gas.

29. Why do different states of matter show different properties?

They show different properties because their particles are arranged differently. Their interparticle attractions and spaces differ.

1. Solids: Closely packed particles.
2. Liquids: Particles move within limited space.
3. Gases: Particles move freely.
4. Final Result: Particle arrangement creates different properties.

30. What are fluids?

Fluids are substances that can flow and do not retain a fixed shape. Liquids and gases are fluids.

1. Liquid: Flows and takes container shape.
2. Gas: Flows and fills available space.
3. Common Property: No fixed shape.
4. Final Result: Liquids and gases are fluids.

31. Why can rice grains and rice flour take the shape of a jar?

Rice grains and rice flour take the shape of the jar because they are collections of many solid particles. Each grain remains solid.

1. Rice Grain: Solid.
2. Rice Flour: Many solid particles.
3. Container Shape: Collection arranges itself.
4. Final Result: Rice and rice flour are solids, not liquids.

Solid Liquid Gas Class 8 Questions

Solid liquid gas class 8 questions focus on fixed shape, fixed volume and particle movement.
Students should avoid only naming examples.
Every answer should mention particle arrangement.

32. What are the properties of solids?

Solids have fixed shape and fixed volume. Their particles are tightly packed with strong attraction.

1. Shape: Fixed.
2. Volume: Fixed.
3. Particles: Vibrate at fixed positions.
4. Final Result: Solids are rigid due to closely packed particles.

33. Why do solids have fixed shape?

Solids have fixed shape because their particles are strongly attracted and fixed in position. They cannot move freely past one another.

1. Attraction: Very strong.
2. Spacing: Minimum.
3. Motion: Only vibration.
4. Final Result: Strong attraction gives solids fixed shape.

34. What are the properties of liquids?

Liquids have fixed volume but no fixed shape. Their particles can move within limited space.

1. Shape: Takes container shape.
2. Volume: Fixed.
3. Particles: Move but stay close.
4. Final Result: Liquids flow but keep fixed volume.

35. Why does water take the shape of a container?

Water takes the shape of a container because its particles can move past one another within limited space. It has no fixed shape.

1. Container A: Water takes one shape.
2. Container B: Water changes shape.
3. Volume: Remains same if not spilled.
4. Final Result: Liquid particles allow shape change.

36. What are the properties of gases?

Gases have no fixed shape and no fixed volume. Their particles move freely in all directions.

1. Shape: Takes container shape.
2. Volume: Fills available space.
3. Particles: Far apart and free.
4. Final Result: Gases fill all available space.

37. Why does smoke spread in a gas jar?

Smoke spreads because gas particles move freely and occupy all available space. Smoke particles are carried by moving air particles.

1. Smoke: Trapped in gas jar A.
2. Second Jar: Smoke enters jar B.
3. Particle Motion: Free movement.
4. Final Result: Gases spread throughout available space.

38. What is the main difference between solids and liquids?

In solids, particles are closely packed and fixed. In liquids, particles remain close but move past each other.

1. Solid Particles: Fixed positions.
2. Liquid Particles: Limited movement.
3. Shape: Solid fixed, liquid not fixed.
4. Final Result: Liquids flow because particles move past one another.

39. What is the main difference between liquids and gases?

Liquids have fixed volume, while gases do not have fixed volume. Gas particles have much larger spaces.

1. Liquid: Particles stay close.
2. Gas: Particles far apart.
3. Volume: Gas fills container.
4. Final Result: Gases have maximum interparticle space.

Melting Point Class 8 Questions

Melting point class 8 questions explain how solids become liquids.
Heating increases particle vibration.
At melting point, particles leave fixed positions and form liquid.

40. What is melting?

Melting is the process in which a solid changes into a liquid on heating. It happens when particles leave fixed positions.

1. Solid: Particles vibrate in fixed positions.
2. Heating: Vibration increases.
3. Liquid: Particles move within limited space.
4. Final Result: Melting changes solid into liquid.

41. What is melting point?

Melting point is the minimum temperature at which a solid melts into a liquid at atmospheric pressure. Ice melts at 0 °C.

1. Definition: Temperature of melting.
2. Condition: Atmospheric pressure.
3. Example: Ice has melting point 0 °C.
4. Final Result: Melting point is a fixed melting temperature.

42. Why do solids melt on heating?

Solids melt because heating increases particle vibration. At enough thermal energy, particles overcome strong attraction.

1. Heat: Adds energy.
2. Vibration: Becomes vigorous.
3. Attraction: Weakens enough for movement.
4. Final Result: Heating allows solid particles to leave fixed positions.

43. Why do different solids have different melting points?

Different solids have different melting points because their interparticle attractions differ. Stronger attraction needs more heat.

1. Ice: Melts at 0 °C.
2. Urea: Melts at 133 °C.
3. Iron: Melts at 1538 °C.
4. Final Result: Stronger attraction gives higher melting point.

44. What is the melting point of ice, urea and iron?

The melting points are 0 °C for ice, 133 °C for urea and 1538 °C for iron. These values show different attraction strengths.

1. Ice: 0 °C.
2. Urea: 133 °C.
3. Iron: 1538 °C.
4. Final Result: Iron has the highest melting point among these.

Boiling Point Class 8 Questions

Boiling point class 8 questions explain how liquids become vapour rapidly.
At boiling point, vapour forms at the surface and inside the liquid.
Bubbles show rapid vapour formation.

45. What is boiling?

Boiling is the rapid conversion of liquid into vapour at a fixed temperature. Vapour forms inside the liquid and at the surface.

1. Liquid: Heated continuously.
2. Bubbles: Vapour forms within liquid.
3. State Change: Liquid becomes vapour.
4. Final Result: Boiling changes liquid into vapour rapidly.

46. What is boiling point?

Boiling point is the temperature at which a liquid boils and turns into vapour at atmospheric pressure. Water boils at about 100 °C.

1. Definition: Temperature of boiling.
2. Condition: Atmospheric pressure.
3. Example: Water boils at about 100 °C.
4. Final Result: Boiling point is the fixed boiling temperature.

47. What happens to liquid particles during boiling?

During boiling, particles gain enough energy to move away from each other. Interparticle attractions decrease strongly.

1. Heat: Increases particle energy.
2. Movement: Becomes vigorous.
3. Escape: Particles leave liquid state.
4. Final Result: Boiling allows particles to become vapour.

48. Why are bubbles seen in boiling water?

Bubbles are seen because vapour forms within the liquid. These vapour bubbles rise to the surface.

1. Water: Heated.
2. Vapour Formation: Occurs inside liquid.
3. Observation: Bubbles appear.
4. Final Result: Boiling produces vapour bubbles inside liquid.

Evaporation Class 8 Questions

Evaporation class 8 questions explain vapour formation below boiling point.
It occurs slowly and only at the surface.
Spilled water disappears because of evaporation.

49. What is evaporation?

Evaporation is the slow conversion of liquid into vapour from its surface at temperatures below boiling point. It can happen at any temperature.

1. Location: Surface only.
2. Speed: Slow.
3. Example: Spilled water disappears.
4. Final Result: Evaporation occurs below boiling point.

50. How is evaporation different from boiling?

Evaporation occurs slowly at the surface, while boiling occurs rapidly throughout the liquid. Boiling happens at boiling point.

1. Evaporation: Surface process.
2. Boiling: Bulk process with bubbles.
3. Temperature: Evaporation can happen below boiling point.
4. Final Result: Evaporation and boiling differ in speed and place.

51. Why does spilled water disappear after some time?

Spilled water disappears because water particles escape from the surface as vapour. This happens through evaporation.

1. Spilled Water: Exposed to air.
2. Surface Particles: Escape slowly.
3. Observation: Water dries.
4. Final Result: Evaporation removes spilled water.

52. Does evaporation occur only at high temperature?

No, evaporation does not occur only at high temperature. It occurs at all temperatures, but faster at higher temperatures.

1. Cold Day: Slow evaporation.
2. Hot Day: Faster evaporation.
3. Reason: Particle movement increases with heat.
4. Final Result: Evaporation can occur at any temperature.

Compressibility of Gases Class 8 Questions

Compressibility of gases class 8 questions explain particle spacing in gases.
Gas particles have large spaces between them.
External pressure can reduce these spaces.

53. Why can air inside a syringe be compressed?

Air can be compressed because gas particles have large spaces between them. Pushing the plunger brings particles closer.

1. Syringe: Filled with air.
2. Thumb: Blocks air escape.
3. Plunger: Reduces volume.
4. Final Result: Air compresses due to large interparticle spaces.

54. Why does the syringe plunger move back when pressure is released?

The plunger moves back because gas particles spread again when pressure is removed. They occupy the available space.

1. Compression: Particles come closer.
2. Release: Particles spread.
3. Plunger: Returns outward.
4. Final Result: Gas particles expand after pressure release.

55. Why is water practically incompressible?

Water is practically incompressible because liquid particles are already close together. There is little space to reduce.

1. Liquid Particles: Close together.
2. Interparticle Space: Small.
3. Compression: Very difficult.
4. Final Result: Liquids are much less compressible than gases.

56. Why can an inflated balloon weigh more than an empty balloon?

An inflated balloon weighs more because air has mass. Extra air particles inside the balloon add weight.

1. Empty Balloon: Contains less air.
2. Inflated Balloon: Contains more air particles.
3. Mass: Increases with added air.
4. Final Result: Air is matter and has mass.

Diffusion Class 8 Questions

Diffusion class 8 questions explain the spreading of particles.
Moving particles spread from one region to another.
Diffusion occurs in liquids and gases.

57. What is diffusion in Class 8 Science?

Diffusion is the spreading of particles of one substance through another due to particle motion. It occurs in liquids and gases.

1. Particles: Move constantly.
2. Spreading: From one region to another.
3. Example: Potassium permanganate spreads in water.
4. Final Result: Diffusion occurs due to particle movement.

58. Why does potassium permanganate spread in water?

Potassium permanganate spreads because water particles are constantly moving. They pull and hit its particles until colour spreads.

1. Initial Observation: Pink streaks appear.
2. Later Observation: Water becomes uniformly pink.
3. Cause: Moving water particles.
4. Final Result: Particle motion spreads potassium permanganate.

59. Why does potassium permanganate spread faster in hot water?

It spreads faster in hot water because particles move faster when heated. More thermal energy increases particle movement.

1. Hot Water: Fastest spreading.
2. Room Temperature Water: Moderate spreading.
3. Ice-cold Water: Slowest spreading.
4. Final Result: Heat increases particle motion.

60. Why does incense stick fragrance spread in a room?

The fragrance spreads because air particles are constantly moving. They carry fragrance particles throughout the room.

1. Source: Burning incense stick.
2. Air Particles: Move continuously.
3. Result: Fragrance reaches distant places.
4. Final Result: Gas particles help fragrance diffuse.

61. Why do gases mix easily?

Gases mix easily because their particles move freely in all directions and have large spaces between them. Interparticle attraction is negligible.

1. Particle Space: Maximum.
2. Motion: Free and random.
3. Attraction: Very weak.
4. Final Result: Gas particles spread and mix easily.

62. Why do solids not mix easily like gases?

Solids do not mix easily because their particles are fixed in position. Strong interparticle attraction prevents free movement.

1. Solid Particles: Closely packed.
2. Attraction: Strong.
3. Motion: Only vibration.
4. Final Result: Solids do not diffuse easily.

Movement of Particles Class 8 Questions

Movement of particles class 8 questions explain how particles behave in different states.
Solids show vibration, liquids show limited movement, and gases show free movement.
Heat increases particle motion.

63. How do particles move in solids?

Particles in solids only vibrate or oscillate about fixed positions. They cannot move freely past one another.

1. Position: Fixed.
2. Motion: Vibration.
3. Attraction: Strong.
4. Final Result: Solid particles have restricted motion.

64. How do particles move in liquids?

Particles in liquids move within limited space. They can move past one another but remain close.

1. Position: Not fixed.
2. Motion: Limited movement.
3. Attraction: Weaker than solids.
4. Final Result: Liquid particles can flow within a limited space.

65. How do particles move in gases?

Particles in gases move freely in all directions. They occupy the entire available space.

1. Position: Not fixed.
2. Spacing: Very large.
3. Attraction: Negligible.
4. Final Result: Gas particles move freely everywhere.

66. How does heat affect particle movement?

Heat increases particle movement. Hot water particles move faster than cold water particles.

1. Cold Water: Slowest particle movement.
2. Room Temperature Water: Moderate movement.
3. Hot Water: Fastest movement.
4. Final Result: Heating increases particle motion.

67. How does thermal energy affect the state of matter?

Thermal energy changes particle motion and attraction. More thermal energy can change solid into liquid and liquid into gas.

1. Solid: Low thermal energy.
2. Liquid: More particle movement.
3. Gas: Particles overcome attraction.
4. Final Result: Thermal energy helps change states of matter.

Particle Arrangement in Solids Liquids and Gases Class 8 Questions

Particle arrangement in solids liquids and gases class 8 questions support diagram-based answers.
Students should draw close packing for solids, loose packing for liquids and widely spaced particles for gases.
The diagrams should show spacing and movement clearly.

68. How should aluminium foil particles be represented?

Aluminium foil particles should be represented as closely packed particles in fixed positions. Aluminium foil is a solid.

1. State: Solid.
2. Spacing: Minimum.
3. Motion: Vibration only.
4. Final Result: Aluminium foil has solid-like particle arrangement.

69. How should glycerin particles be represented?

Glycerin particles should be represented as close but movable particles. Glycerin is a liquid.

1. State: Liquid.
2. Spacing: More than solid.
3. Motion: Limited movement.
4. Final Result: Glycerin has liquid-like particle arrangement.

70. How should methane gas particles be represented?

Methane gas particles should be represented as far apart and freely moving. Methane is a gas.

1. State: Gas.
2. Spacing: Maximum.
3. Motion: Free movement.
4. Final Result: Methane has gas-like particle arrangement.

71. How does particle arrangement change from ice to water vapour?

Ice particles are closely packed, water particles move within limited space, and water vapour particles move freely. Heating increases spacing and movement.

1. Ice: Solid with fixed particles.
2. Water: Liquid with moving particles.
3. Water Vapour: Gas with free particles.
4. Final Result: Heating changes particle arrangement from fixed to free.

NCERT Class 8 Science Chapter 7 Questions

NCERT Class 8 Science Chapter 7 questions test particle arrangement, states of matter, melting, diffusion and daily observations.
Students should justify each answer using particle movement and spacing.
These NCERT Class 8 Science Chapter 7 questions follow the 2026 exercise pattern.

72. Which statement best compares particles in solids and liquids?

The correct statement is constituent particles are closely packed in solids and move past each other in liquids. Solids have fixed positions, while liquids flow.

1. Solid: Closely packed particles.
2. Liquid: Particles move past each other.
3. Correct Option: iv.
4. Final Result: Liquids flow because particles can move past one another.

73. Is melting ice into water a solid-to-liquid transformation?

Yes, melting ice into water is a solid-to-liquid transformation. Heating changes particle arrangement.

1. Initial State: Ice is solid.
2. Final State: Water is liquid.
3. Process: Melting.
4. Final Result: Ice melting is solid to liquid change.

74. Does melting involve a decrease in interparticle attraction?

Yes, melting involves a decrease in effective interparticle attraction. Particles gain energy and leave fixed positions.

1. Heating: Adds energy.
2. Particles: Vibrate more.
3. Attraction Effect: Weakens enough for movement.
4. Final Result: Melting weakens solid-like particle holding.

75. Do solids have fixed shape and fixed volume?

Yes, solids have fixed shape and fixed volume. Strong interparticle attraction keeps particles fixed.

1. Shape: Fixed.
2. Volume: Fixed.
3. Reason: Strong attraction.
4. Final Result: Solids retain shape and volume.

76. Are interparticle interactions in solids very strong?

Yes, interparticle interactions in solids are very strong. Interparticle spaces are also very small.

1. Attraction: Very strong.
2. Spacing: Minimum.
3. Motion: Vibration only.
4. Final Result: Solids have strong attraction and small spaces.

77. Why does camphor fragrance reach all corners of a room?

Camphor fragrance reaches all corners because vapour particles spread through moving air particles. This is diffusion in gases.

1. Camphor: Gives vapour.
2. Air Particles: Move constantly.
3. Result: Fragrance spreads.
4. Final Result: Gas diffusion spreads camphor fragrance.

78. Is smell released because energy becomes smell?

No, energy does not become smell. Heating helps camphor particles escape and spread through air.

1. Heat: Gives particles energy.
2. Camphor Particles: Spread as vapour.
3. Smell: Due to camphor particles reaching nose.
4. Final Result: Smell comes from particles, not released energy.

79. What happens if all constituent particles are removed from a chair?

Nothing of the chair will remain if all its constituent particles are removed. Matter exists because of its particles.

1. Chair: Made of particles.
2. Remove Particles: Remove matter.
3. Result: Chair disappears.
4. Final Result: A chair cannot exist without particles.

80. Why do gases mix easily while solids do not?

Gases mix easily because particles move freely and have large spaces. Solids do not mix easily because particles are fixed.

1. Gases: Free moving particles.
2. Solids: Fixed particles.
3. Attraction: Stronger in solids.
4. Final Result: Particle movement makes gases mix easily.

81. Why does milk spread when spilled but the glass tumbler keeps its shape?

Milk spreads because it is a liquid with no fixed shape. The glass tumbler keeps its shape because it is a solid.

1. Milk: Liquid particles move.
2. Glass: Solid particles fixed.
3. Result: Milk flows, glass stays shaped.
4. Final Result: Liquids flow while solids retain shape.

82. What states of wax appear in a burning candle?

A burning candle shows solid wax, liquid wax and wax vapour. Heat changes wax from solid to liquid and then vapour.

1. Solid Wax: Unmelted candle.
2. Liquid Wax: Melted wax near flame.
3. Vapour: Wax vapour burns near wick.
4. Final Result: Candle wax can exist in three states.

83. Are grains of rice and rice flour solids or liquids?

Grains of rice and rice flour are solids. They take container shape only as collections of many separate solid particles.

1. Rice Grain: Solid particle.
2. Rice Flour: Powdered solid.
3. Container Shape: Due to piling and settling.
4. Final Result: Rice and rice flour are solids.

Class 8 Science Chapter 7 Questions and Answers

Class 8 Science Chapter 7 questions and answers should explain visible events through invisible particles.
Students should mention particle spacing, attraction or movement in every answer.
These answers support quick revision for school tests.

84. Why can stones or sand be piled up, but water cannot?

Stones and sand can be piled because their particles or grains retain fixed shape. Water flows because liquid particles move past one another.

1. Stones: Solid pieces.
2. Sand: Collection of solid grains.
3. Water: Liquid that flows.
4. Final Result: Solids can pile, liquids flow.

85. Why does water take the shape of folded hands?

Water takes the shape of folded hands because it is a liquid. It has fixed volume but no fixed shape.

1. Container: Folded hands.
2. Water: Takes available shape.
3. Release: Water loses that shape.
4. Final Result: Liquid shape depends on container.

86. Why does perfume fragrance reach us from a distance?

Perfume fragrance reaches us because its particles diffuse through air. Air particles are constantly moving.

1. Perfume: Releases fragrance particles.
2. Air: Contains moving particles.
3. Diffusion: Spreads fragrance.
4. Final Result: Gas diffusion carries perfume smell.

87. Why does soap help remove oil stains?

Soap helps remove oil stains because soap particles surround oil particles. One end attaches to oil, and another mixes with water.

1. Oil: Sticks to fabric.
2. Soap Particles: Surround oil.
3. Water: Washes lifted oil away.
4. Final Result: Soap particles help detach oil from cloth.

88. Why is air we breathe today connected with air from long ago?

Air particles keep moving, mixing and circulating through the atmosphere. This continuous motion means gases spread across large distances over time.

1. Air: Mixture of gases.
2. Particle Motion: Constant.
3. Mixing: Happens over time.
4. Final Result: Air particles continuously mix in the atmosphere.

89. What happens when a balloon fixed on a bottle is placed in hot water?

The balloon inflates because air inside the bottle gets heated and expands. Gas particles move faster and occupy more space.

1. Bottle Air: Gets heated.
2. Gas Particles: Move faster.
3. Balloon: Expands.
4. Final Result: Heating air makes it expand.

90. Why is iodine vapour used to show gas behaviour?

Iodine vapour spreads freely inside a closed jar. It helps show that gas particles move and fill available space.

1. Solid Iodine: Produces vapour.
2. Vapour: Spreads in jar.
3. Observation: Gas fills available space.
4. Final Result: Iodine vapour shows gas particle movement.

91. Why are gases useful and sometimes harmful because they spread?

Gases are useful because oxygen spreads through air, but harmful gases can also spread quickly. This property depends on gas particle movement.

1. Useful Example: Oxygen spreads for breathing.
2. Harmful Example: Smoke spreads in air.
3. Cause: Free gas particle motion.
4. Final Result: Gas spreading can help or harm life.

Class 8 Science Chapter List