What is Particulate Matter Exercises in Class 8 Science NCERT?

The Class 8 Science NCERT Chapter 7 — Particulate Nature of Matter exercise section tests students on all the key concepts covered in the chapter, including NCERT exercises, particle questions, diffusion questions, competency-based questions. It includes multiple-choice questions (MCQs), assertion-…

What does the NCERT Class 8 Science Particulate Nature of Matter exercise section cover?

The Class 8 Science NCERT Chapter 7 u2014 Particulate Nature of Matter exercise section tests students on all the key concepts covered in the chapter, including NCERT exercises, particle questions, diffusion questions, competency-based questions. It includes multiple-choice questions (MCQs), assertion-reason questions, short-answer questions, long-answer questions, and competency-based questions that align with the NCERT Curiosity textbook. Working through these exercises helps Class 8 students reinforce their conceptual understanding, prepare for classroom assessments, and build exam readiness for CBSE school tests. Each question links back to a specific section of the chapter so students can revise the theory alongside the practice.

How should Class 8 students approach the Particulate Nature of Matter exercises?

Class 8 students should approach the Particulate Nature of Matter exercises by first revising the main theory and definitions from each part of the chapter, especially around NCERT exercises and particle questions. Start with the MCQs and assertion-reason questions to quickly test recall, then attempt the short-answer questions that need a one or two-line explanation, and finally tackle the long-answer and competency-based questions that require applying concepts to new situations. Write neat diagrams wherever the question involves a process, cycle, or setup, and always use NCERT-style vocabulary in your answers to match CBSE marking schemes.

Are these Particulate Nature of Matter questions competency-based as per NEP 2020?

Yes, the Particulate Nature of Matter exercise set follows the NEP 2020 competency-based education (CBE) framework used by CBSE and NCERT for Class 8 Science. Instead of only asking students to recall definitions, many questions are scenario-based and require applying the concept to real-life situations, analysing data, or evaluating claims. This matches Bloom's Taxonomy levels L3 (Apply), L4 (Analyse), and L5 (Evaluate), going beyond rote learning. Students practising these questions build the higher-order thinking skills that modern CBSE school exams increasingly assess, and also prepare well for competitive foundation tests in later years.

Which NCERT Curiosity sections are tested in Chapter 7 exercises?

The Chapter 7 u2014 Particulate Nature of Matter exercise set systematically tests every major section of the NCERT Curiosity Class 8 Science textbook for this chapter. Topics covered include NCERT exercises, particle questions, diffusion questions, competency-based questions. Every in-text question, activity-linked question, and end-of-chapter question from the Curiosity book is represented, so students can be confident that completing this exercise set gives them full coverage of the NCERT syllabus. Teachers also frequently pick questions from these sections for school unit tests and half-yearly exams, making thorough practice essential for strong performance.

How do assertion-reason questions work in this Class 8 Science chapter?

Assertion-reason questions in the Class 8 Science Particulate Nature of Matter exercise set present two statements u2014 an Assertion (A) and a Reason (R) u2014 and ask students to judge whether each is true and whether R correctly explains A. Students pick from four standard options: both true with R explaining A, both true but R not explaining A, A true and R false, or A false. This format tests whether Class 8 learners genuinely understand the cause-and-effect relationships behind NCERT exercises, not just surface facts. Mastering this format is valuable because CBSE Class 10 board exams use the same pattern.

What is the best revision strategy before attempting these exercises?

The best revision strategy before attempting Particulate Nature of Matter exercises is to read through all theory parts of NCERT Curiosity Chapter 7 once, write down the key terms such as NCERT exercises, particle questions, diffusion questions, competency-based questions in your own words, and then re-do all activities mentally to understand the underlying concept. Next, make a one-page mind map linking the main ideas. Only then attempt the exercise questions u2014 first without looking back, then self-correcting. This active-recall approach builds much stronger long-term memory than repeatedly re-reading the textbook, and is widely recommended by CBSE teachers for Class 8 Science preparation.

What does the NCERT Class 8 Science Particulate Nature of Matter exercise section cover?

The Class 8 Science NCERT Chapter 7 — Particulate Nature of Matter exercise section tests students on all the key concepts covered in the chapter, including NCERT exercises, particle questions, diffusion questions, competency-based questions. It includes multiple-choice questions (MCQs), assertion-reason questions, short-answer questions, long-answer questions, and competency-based questions that align with the NCERT Curiosity textbook. Working through these exercises helps Class 8 students reinforce their conceptual understanding, prepare for classroom assessments, and build exam readiness for CBSE school tests. Each question links back to a specific section of the chapter so students can revise the theory alongside the practice.

How should Class 8 students approach the Particulate Nature of Matter exercises?

Class 8 students should approach the Particulate Nature of Matter exercises by first revising the main theory and definitions from each part of the chapter, especially around NCERT exercises and particle questions. Start with the MCQs and assertion-reason questions to quickly test recall, then attempt the short-answer questions that need a one or two-line explanation, and finally tackle the long-answer and competency-based questions that require applying concepts to new situations. Write neat diagrams wherever the question involves a process, cycle, or setup, and always use NCERT-style vocabulary in your answers to match CBSE marking schemes.

Are these Particulate Nature of Matter questions competency-based as per NEP 2020?

Yes, the Particulate Nature of Matter exercise set follows the NEP 2020 competency-based education (CBE) framework used by CBSE and NCERT for Class 8 Science. Instead of only asking students to recall definitions, many questions are scenario-based and require applying the concept to real-life situations, analysing data, or evaluating claims. This matches Bloom's Taxonomy levels L3 (Apply), L4 (Analyse), and L5 (Evaluate), going beyond rote learning. Students practising these questions build the higher-order thinking skills that modern CBSE school exams increasingly assess, and also prepare well for competitive foundation tests in later years.

Which NCERT Curiosity sections are tested in Chapter 7 exercises?

The Chapter 7 — Particulate Nature of Matter exercise set systematically tests every major section of the NCERT Curiosity Class 8 Science textbook for this chapter. Topics covered include NCERT exercises, particle questions, diffusion questions, competency-based questions. Every in-text question, activity-linked question, and end-of-chapter question from the Curiosity book is represented, so students can be confident that completing this exercise set gives them full coverage of the NCERT syllabus. Teachers also frequently pick questions from these sections for school unit tests and half-yearly exams, making thorough practice essential for strong performance.

How do assertion-reason questions work in this Class 8 Science chapter?

Assertion-reason questions in the Class 8 Science Particulate Nature of Matter exercise set present two statements — an Assertion (A) and a Reason (R) — and ask students to judge whether each is true and whether R correctly explains A. Students pick from four standard options: both true with R explaining A, both true but R not explaining A, A true and R false, or A false. This format tests whether Class 8 learners genuinely understand the cause-and-effect relationships behind NCERT exercises, not just surface facts. Mastering this format is valuable because CBSE Class 10 board exams use the same pattern.

What is the best revision strategy before attempting these exercises?

The best revision strategy before attempting Particulate Nature of Matter exercises is to read through all theory parts of NCERT Curiosity Chapter 7 once, write down the key terms such as NCERT exercises, particle questions, diffusion questions, competency-based questions in your own words, and then re-do all activities mentally to understand the underlying concept. Next, make a one-page mind map linking the main ideas. Only then attempt the exercise questions — first without looking back, then self-correcting. This active-recall approach builds much stronger long-term memory than repeatedly re-reading the textbook, and is widely recommended by CBSE teachers for Class 8 Science preparation.

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Particulate Nature of Matter — Exercises

🎓 Class 8 Science CBSE Theory Ch 7 — Conservation of Plants and Animals ⏱ ~21 min

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Chapter Summary

Matter is anything that has mass and occupies space.
Matter is made of extremely tiny particles — atoms and molecules. This idea was first proposed by Kanad (India) and Democritus (Greece).
Particles of matter are tiny, always in motion, have spaces between them, and attract each other.
In solids, particles are tightly packed with strong forces and fixed positions.
In liquids, particles are close but can slide; liquids flow and take the container's shape.
In gases, particles are far apart, move freely and forces are very weak; gases fill any container.
Diffusion is the spontaneous mixing of particles; it is fastest in gases, slower in liquids, very slow in solids.
Higher temperature speeds up particle motion and therefore diffusion.
Changes of state (melt, freeze, boil, condense) only rearrange particles — no new substance is made.
Brownian motion — random zig-zag dance of fine particles in a fluid — proves that particles are in constant motion.

Keywords at a Glance

MatterAnything that has mass and occupies space.

ParticleAtom or molecule — the tiny building block of matter.

ParamanuKanad's ancient name for the smallest indivisible particle.

AtomSmallest particle of an element, ~10⁻¹⁰ m across.

Interparticle spacingAverage distance between neighbouring particles.

DiffusionSpontaneous mixing of particles of one substance into another.

CompressibilityAbility of a material to reduce volume when squeezed.

Change of stateSolid ↔ liquid ↔ gas transformation driven by heating or cooling.

Brownian motionRandom zig-zag motion of small suspended particles in a fluid.

EvaporationSurface-level change of a liquid into gas below its boiling point.

NCERT Exercises — Solved

What is matter? Give five examples.

Solution: Matter is anything that has mass and occupies space. Examples: (i) water (liquid), (ii) stone (solid), (iii) iron nail (solid), (iv) air inside a balloon (gas), (v) milk (liquid). Other valid examples: sugar, sand, oxygen, wood, ice.

What evidence proves that matter is made of particles?

Solution:

Sugar in water: adding sugar to a filled glass of water does not make it overflow — sugar particles fit into spaces between water particles.
Smell spreading: the fragrance of flowers or cooking food reaches every corner of a room — gas particles move and mix.
Ink in water: a drop of ink spreads through still water without stirring — particles of both move and mix.
Potassium permanganate: its purple colour diffuses through water on its own.
Steam from a cooker: gas particles under pressure rush out of the whistle with force.

All these would be impossible if matter were continuous; they only make sense if matter is built of moving particles with gaps between them.

Why does the volume of water not change when sugar is added to it?

Solution: Water is not a solid block — there are tiny empty spaces between its particles. When sugar dissolves, the sugar particles slip neatly into these gaps. Because the sugar fills existing space instead of adding new space, the overall volume of the mixture stays almost the same.

We can pile up stones or sand but not water. Explain in terms of particles.

Solution: In stones and sand (solids), the particles are packed very close together with strong attractive forces that hold every particle in a fixed position. So the shape stays — we can heap them. In water (a liquid), particles are still close, but the forces between them are weaker, so particles slide freely past one another. Water therefore flows and spreads flat under gravity instead of piling up.

Why does the smell of a deodorant or perfume spread across a room?

Solution: Particles of the perfume escape into the air as a gas. Both perfume particles and air particles are in rapid, random motion. The perfume particles travel through the gaps between air particles and reach every corner of the room. This spontaneous mixing is called diffusion in gases.

On heating camphor in one corner of a room, its fragrance reaches every corner. Why? Explain the role of heat energy.

Solution: Heating gives camphor particles extra energy. This energy breaks the forces holding them in the solid, turning them directly into vapour (sublimation). The vapour particles, full of energy, move fast and diffuse rapidly through the air, carrying the fragrance across the room. In short: heat → faster, more energetic particles → faster diffusion.

If we could remove all the constituent particles of a chair, what would happen? Choose with justification.
(a) Nothing changes (b) The chair will weigh less (c) The chair will have no lost particles (d) Nothing of the chair will remain.

Correct answer: (d) Nothing of the chair will remain.
Justification: A chair is nothing but a collection of particles (wood or plastic or metal atoms and molecules) arranged in a particular shape. Remove every particle and you remove the chair itself — there is no "chair" left behind separate from its particles.

Why do gases diffuse easily while solids hardly diffuse at all?

Solution: In gases, particles are very far apart, experience almost no attractive forces, and move at high speeds in random directions. They easily slip through the gaps between other gas particles, so mixing is quick. In solids, particles are packed very tightly, held by very strong forces, and can only vibrate in fixed positions. There is almost no room and no free motion, so diffusion is extremely slow.

When spilled on a table, milk from a glass tumbler flows and spreads out, but the tumbler itself keeps its shape. Justify.

Solution: The tumbler is a solid. Its particles are locked tightly by strong forces in fixed positions, so its shape does not change on falling. The milk inside is a liquid. Its particles are close but free to slide past each other, so when the tumbler tips, the milk loses its original shape and spreads flat across the table.

Q10

Represent diagrammatically the changes in arrangement of particles as ice melts and then turns into water vapour.

Solution:

As ice turns to water, spacing grows slightly and particles start sliding. As water turns to vapour, spacing grows enormously and particles fly apart freely.

Q11

Draw pictures representing the particles in: (i) Aluminium foil, (ii) Glycerin, (iii) Methane gas.

Solution:

Aluminium foil: particles packed tightly in a neat grid. Glycerin: particles close but irregular, able to slide. Methane: particles far apart and scattered.

Q12

Fig 7.16(a) shows a burning candle. Where has the wax gone? Fig 7.16(b) shows the arrangement of particles. Explain.

Solution: The solid wax near the wick first melts into liquid wax (the pool at the top of the candle). The liquid wax is drawn up the wick and there the heat turns it into wax vapour. The vapour burns — combining with oxygen from the air — to form carbon dioxide gas and water vapour, which escape into the surrounding air.

So the wax hasn't vanished — it has been converted into invisible gases that diffuse into the air.

Q13

Why does ocean water taste salty even though we cannot see any salt in it?

Solution: Salt (common salt — sodium chloride) is made of tiny particles. When salt dissolves in sea water, these particles separate completely and spread into the spaces between water particles. They become so small and so evenly distributed that light passes through the mixture and we cannot see them. But our tongue's taste buds can still detect them chemically, so the water tastes salty. This is identical to Activity 7.1 — sugar "disappearing" in water at home.

Q14

Rice grains and rice flour both take the shape of the container they are poured into. Are they solids or liquids? Explain.

Solution: Each individual rice grain and each tiny speck of rice flour is a solid — they have a definite shape and their particles are tightly packed. What changes shape is the heap of many grains or specks together, not each grain itself. Because the grains are small and roll over each other, a heap can take the shape of its container. So rice grains and rice flour are collections of solids that behave like liquids when poured — but the material itself is not a liquid.

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