---
title: "NCERT Solutions Class 8 Science Ch 7 Particulate Nature of Matter"
url: https://www.swavid.com/science/class/8/chapter/particulate-nature-of-matter/ncert-solutions
dateModified: 2026-10-07T16:14:45+00:00
---

# NCERT Solutions Class 8 Science Ch 7 Particulate Nature of Matter

This chapter's questions cover concepts related to the particulate nature of matter, the three states of matter, interparticle spacing, attractive forces, and the movement of particles. Students explore these physical properties through various activities, exercises, and critical thinking problems.

Free PDF (13 pages): https://www.swavid.com/api/seo/pdf/ncert/science/class-8/swavid-ncert-solutions-class-8-science-chapter-7-particulate-nature-of-matter-7cb91bb328.pdf

## Probe and ponder

### Question 1

*3 marks · Short answer*

Why is it possible to pile up stones or sand, but not a liquid like water?

**Solution**

1. Stones and sand are solids, which have strong interparticle forces of attraction holding particles in fixed positions.
2. This allows solids to maintain a definite shape and be piled up.
3. Liquids like water have weaker interparticle attractions, allowing particles to move freely and flow, which prevents them from being piled up.

**Answer:** Solids can be piled because their particles are held in fixed positions by strong attractions, whereas liquid particles move freely and flow, making piling impossible.

> Common mistake: Confusing the property of 'flow' with the strength of interparticle attraction.

### Question 2

*3 marks · Short answer*

Why does water take the shape of folded hands but lose that shape when released?

**Solution**

1. Liquids do not have a fixed shape and take the shape of the container or surface they are in.
2. The particles in liquids are free to move within a limited space.
3. When released, the liquid flows due to the freedom of movement of its particles, causing it to lose the shape it held in the folded hands.

**Answer:** Water takes the shape of folded hands because it is a liquid, but it loses that shape when released because its particles are free to move and flow.

> Common mistake: Failing to mention that liquids do not have a fixed shape.

### Question 3

*3 marks · Short answer*

We cannot see air, so how does it add weight to an inflated balloon?

**Solution**

1. Matter is composed of extremely small particles that have mass.
2. Air is a form of matter, and even though its particles are invisible, they possess mass.
3. When we inflate a balloon, we are filling it with a large number of these air particles, which collectively add weight to the balloon.

**Answer:** Air is matter made of tiny particles that have mass; filling a balloon with these particles increases its total weight.

> Common mistake: Thinking that invisible things cannot have weight.

### Question 4

*3 marks · Short answer*

Is the air we breathe today the same that existed thousands of years ago?

**Solution**

1. Matter is made up of tiny, eternal particles called Parmanu or atoms.
2. These fundamental building blocks of matter do not change their nature over time.
3. Therefore, the constituent particles of the air we breathe today are the same as those that existed thousands of years ago.

**Answer:** Yes, the air is composed of the same fundamental constituent particles (atoms and molecules) that have existed for thousands of years.

> Common mistake: Confusing the composition of air (the mixture of gases) with the nature of the particles themselves.

### Question 5

*3 marks · Short answer*

Share your questions 
 _________ ?

**Solution**

1. A relevant question based on the chapter is: 'If particles are always in motion, why do solids maintain a fixed shape?'
2. This question explores the relationship between thermal energy and interparticle attraction.
3. It helps us understand why the movement in solids is restricted to only small vibrations.

**Answer:** My question is: If particles are always in motion, why do solids maintain a fixed shape?

> Common mistake: Asking a question unrelated to the particulate nature of matter.

## Activity 7.1: Let us explore

### Question 1

*Activity*

What do you observe?

**Solution**

1. Each tiny grain obtained after grinding the chalk is still a speck of chalk.

**Answer:** Each tiny grain observed is still a speck of chalk.

### Question 2

*Activity*

Is every speck of this fine chalk powder still composed of the same substance, or has it changed into something else on breaking or grinding?

**Solution**

1. Grinding chalk is a physical change in which the size of each speck of chalk has reduced further.
2. The chalk does not change into a new substance on breaking or grinding, so every speck is still composed of the same substance.

**Answer:** Every speck of the fine chalk powder is still composed of the same substance and has not changed into a new substance.

## Activity 7.2: Let us perform

### Question 1

*2 marks · Very short answer*

Are the units of chalk obtained in this manner considered the smallest units of chalk?

**Solution**

1. The tiny units of chalk obtained by continuous grinding are the basic building blocks of chalk.
2. However, they are still made up of millions of constituent particles and can be broken down further until we reach the ultimate constituent particles.

**Answer:** No, the units obtained by grinding are not the absolute smallest units, as they are further made up of constituent particles.

> Common mistake: Thinking that visible fine powder is the smallest possible unit of matter.

### Question 2

*2 marks · Very short answer*

Does the water taste sweet?

**Solution**

1. When two teaspoons of sugar are added to water without stirring, sugar settles at the bottom and the top layer of water remains plain.
2. Therefore, the water from the top layer does not taste sweet initially.

**Answer:** No, the water from the top layer does not taste sweet before stirring.

> Common mistake: Assuming sugar mixes instantly throughout the water without stirring.

### Question 3

*2 marks · Very short answer*

What difference in taste do you notice? Does it taste sweet?

**Solution**

1. After stirring the water completely, the sugar dissolves and spreads uniformly throughout the solution.
2. As a result, a spoonful of water from the top layer tastes sweet due to the presence of dissolved sugar particles.

**Answer:** Yes, after stirring, the top layer of water tastes sweet because the sugar particles dissolve and spread throughout the solution.

> Common mistake: Thinking sugar disappears completely rather than breaking into constituent particles.

## Activity 7.3 : Let us find out

### Question 1

*3 marks · Short answer*

In which of the above six objects do you think particles are strongly held together?

**Solution**

1. All the six objects shown in Fig. 7.3 (iron nail, rock salt, stone, wooden block, key, and piece of aluminium) are solids.
2. In solids, the particles are tightly packed and held together by very strong interparticle forces of attraction.
3. Therefore, the particles are strongly held together in all of these six solid objects.

**Answer:** Particles are strongly held together in all the six solid objects (iron nail, rock salt, stone, wooden block, key, and piece of aluminium) because they are solids with strong interparticle attractions.

> Common mistake: Thinking that only metals like iron have strong interparticle forces while ignoring other solids like wood, salt, or stone.

## Activity 7.4: Let us try and find out

### Question 1

*Activity*

Are you able to move your finger through the water?

**Solution**

1. Take some water in a shallow vessel and try to move your finger through it as shown in Fig. 7.6.
2. You are able to move your finger through water without permanently breaking or cutting it.
3. This happens because interparticle attractions in liquids are slightly weaker than in solids, allowing temporary displacement of water which is restored as soon as you remove your finger.

**Answer:** Yes, we are able to move our finger through water by temporarily displacing it because the interparticle attractions in liquids are weaker than in solids.

> Common mistake: Thinking that water gets permanently cut or broken when a finger is moved through it.

## Activity 7.6: Let us experiment

### Question 1

*Activity*

What do you observe?

**Solution**

1. When the plunger is pushed inward with the open end closed, the volume of air inside the syringe decreases.
2. This shows that gas particles have a lot of space between them, which can be reduced by applying external pressure.

**Answer:** The volume of air inside the syringe decreases as the gas particles are forced closer together.

> Common mistake: Thinking that the air inside disappears rather than being compressed into a smaller volume.

## Activity 7.7: Let us observe

### Question 1

*Activity*

What difference do you observe in the water levels?

**Solution**

1. Initially, when sugar is added to water, the water level rises.
2. After stirring and complete dissolution of sugar, the water level decreases to some extent.
3. This indicates that there is space between water particles, and the dissolved sugar particles occupy these interparticle spaces without significantly increasing the total volume.

**Answer:** The water level rises initially on adding sugar, but after dissolution, it decreases slightly as sugar particles occupy the interparticle spaces between water particles.

> Common mistake: Thinking that the total volume of a solution is always equal to the sum of the volumes of the solute and solvent.

### Question 2

*Activity*

What do you observe in each case? Do the sand particles dissolve? Does the volume of water in the vessel change after mixing, and why?

**Solution**

1. Soluble solids like common salt or glucose dissolve in water by occupying the spaces between water particles, keeping the volume change minimal.
2. Insoluble solids like sand do not dissolve in water; their particles simply settle down at the bottom.
3. When sand is added, the sand particles occupy space in the container alongside water, causing the total volume to increase.

**Answer:** Soluble solids dissolve and occupy interparticle spaces with little volume change, whereas insoluble solids like sand do not dissolve, settle down, and cause the total volume to increase.

> Common mistake: Assuming all solids dissolve in water and behave the same way.

## Activity 7.8: Let us experiment

### Question 1

*Activity*

What do you observe?

**Solution**

1. Initially, streaks of pink colour spread out from the potassium permanganate grain into the water.
2. With the passage of time, the entire bulk of water acquires a uniform pink colour due to the constant motion of water particles.

**Answer:** Initially streaks of pink colour spread out, and finally the entire bulk of water acquires a uniform pink colour.

> Common mistake: Thinking that stirring is required for the pink colour to spread throughout the water.

## Activity 7.9: Let us find out

### Question 1

*Activity*

Do you notice the fragrance from a distance?

**Solution**

1. When an incense stick is lit in one corner of the room, the fragrance is initially felt only around the stick.
2. With the passage of time, the fragrance spreads and can be smelled from a distance throughout the room.
3. This activity demonstrates that gas particles are in constant motion and mix with air particles to fill the entire space.

**Answer:** Yes, the fragrance can be noticed from a distance as gas particles spread throughout the room due to constant motion.

## Keep the curiosity alive

### Question 1

*1 mark · MCQ*

The primary difference between solids and liquids is that the constituent particles are:

- closely packed in solids, while they are stationary in liquids.
- far apart in solids and have fixed position in liquids.
- always moving in solids and have fixed position in liquids.
- closely packed in solids and move past each other in liquids.

**Solution**

1. In solids, particles are closely packed and cannot move freely from their positions.
2. In liquids, particles are also close but can move and slide past each other, giving the correct option.

**Answer:** (iv) closely packed in solids and move past each other in liquids.

> Common mistake: Thinking particles in liquids are stationary.

### Question 2

*5 marks · Case-based*

Which of the following statements are true? Correct the false statements.
(i) Melting ice into water is an example of the transformation of a solid into a liquid.
(ii) Melting process involves a decrease in interparticle attractions during the transformation.
(iii) Solids have a fixed shape and a fixed volume.
(iv) The interparticle interactions in solids are very strong, and the interparticle spaces are very small.
(v) When we heat camphor in one corner of a room, the fragrance reaches all corners of the room.
(vi) On heating, we are adding energy to the camphor, and the energy is released as a smell.

**Part (i)**

1. Melting ice absorbs heat and turns into liquid water, which is a solid to liquid transformation.

Answer (i): True

**Part (ii)**

1. Melting involves an increase in thermal energy which overcomes interparticle attractions, causing them to decrease.

Answer (ii): False. Melting process involves a decrease in interparticle attractions during the transformation.

**Part (iii)**

1. Solids possess strong interparticle forces and fixed particle positions, giving them a definite shape and volume.

Answer (iii): True

**Part (iv)**

1. In solids, particles are tightly held by very strong interparticle interactions with minimal empty space between them.

Answer (iv): True

**Part (v)**

1. Heating camphor causes sublimation, and the gaseous particles spread across the room through constant motion.

Answer (v): True

**Part (vi)**

1. Heating adds energy that helps particles overcome attractive forces, but the smell is due to the spread of particles, not released energy.

Answer (vi): False. On heating, we are adding thermal energy to particles, which helps them overcome forces of attraction and spread out as a gas.

**Answer:** Statements (i), (iii), (iv), and (v) are true; statements (ii) and (vi) are false.

> Common mistake: Confusing the decrease in attraction with an increase during melting.

### Question 3

*1 mark · MCQ*

If we could remove all the constituent particles from a chair, what would happen?

- Nothing will change.
- The chair will weigh less due to lost particles.
- Nothing of the chair will remain.

**Solution**

1. Matter is entirely composed of its constituent particles.
2. If all constituent particles are removed, nothing of the object remains.

**Answer:** (iii) Nothing of the chair will remain.

> Common mistake: Choosing option (ii) thinking some weight or mass would remain without particles.

### Question 4

*3 marks · Short answer*

Why do gases mix easily, while solids do not?

**Solution**

1. In gases, interparticle attractions are negligible and particles have large interparticle spaces, allowing them to move freely in all directions and mix easily.
2. In solids, particles are closely packed with very strong interparticle attractions and fixed positions.
3. Due to this restricted motion and strong binding, solids cannot mix easily like gases.

**Answer:** Gases mix easily because their particles move freely with negligible interparticle forces, whereas solid particles are tightly held in fixed positions.

> Common mistake: Forgetting to mention interparticle spacing and forces.

### Question 5

*3 marks · Short answer*

When spilled on the table, milk in a glass tumbler, flows and spreads out, but the glass tumbler stays in the same shape. Justify this statement.

**Solution**

1. Milk is a liquid, which means its particles are free to move within a limited space and it has no fixed shape.
2. When spilled on a table, milk flows and spreads out to take the shape of the surface because of the free movement of its particles.
3. When kept inside a glass tumbler, milk takes the shape of the tumbler, while the solid glass tumbler maintains its own rigid shape due to strong interparticle attractions.

**Answer:** Milk flows because liquids lack a fixed shape and take the shape of their container, while the glass tumbler remains rigid because it is a solid.

> Common mistake: Confusing the behavior of the liquid with the solid container.

### Question 6

*5 marks · Long answer*

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

**Solution**

1. Diagram: Draw three sequential boxes showing particle arrangements for solid (ice), liquid (water), and gas (water vapour).
2. In the solid state (ice), particles are closely packed in a regular arrangement with minimum interparticle space and strong attractive forces.
3. When heat is supplied, ice melts into a liquid where particles gain thermal energy, become slightly farther apart, and can move around within a limited space.
4. With further heating to vaporization, particles gain enough energy to completely overcome interparticle attractions, resulting in maximum spacing and completely free movement in all directions as water vapour.

**Answer:** As ice melts into water and transforms into vapour, the particles move from a tightly packed fixed arrangement to a loosely arranged state, and finally to widely separated free particles.

> Common mistake: Drawing the same particle spacing for all three states of matter.

### Question 7

*3 marks · Short answer*

Draw a picture representing particles present in the following:
(i) Aluminium foil
(ii) Glycerin
(iii) Methane gas

**Part (i)**

1. Aluminium foil is a solid.
2. Draw a diagram showing particles tightly packed in a regular, fixed pattern with minimum interparticle spacing.

Answer (i): Tightly packed particles in a regular arrangement representing a solid.

**Part (ii)**

1. Glycerin is a liquid.
2. Draw a diagram showing particles close to each other but slightly more spaced out and free to move than in solids.

Answer (ii): Close but slightly loose packing representing a liquid.

**Part (iii)**

1. Methane is a gas.
2. Draw a diagram showing particles far apart with large interparticle spaces and random motion.

Answer (iii): Widely separated particles representing a gas.

**Answer:** Represented by three diagrams showing tightly packed regular arrangement for aluminium foil, closely packed irregular arrangement for glycerin, and widely separated arrangement for methane gas.

> Common mistake: Drawing the same particle spacing for all three states of matter.

### Question 8

*3 marks · Short answer*

Observe Fig. 7.16a which shows the image of a candle that was just extinguished after burning for some time. Identify the different states of wax in the figure and match them with Fig. 7.16b showing the arrangement of particles.

**Solution**

1. Identify the states of wax in Fig. 7.16a: solid wax at the base, liquid wax near the wick/cup, and gaseous wax (vapour) rising from the wick.
2. Match solid wax with the tightly packed particle arrangement (solid state).
3. Match liquid wax with the slightly less closely packed arrangement (liquid state) and gaseous wax with the widely separated particles (gaseous state).

**Answer:** Solid wax matches the tightly packed particle arrangement, liquid wax matches the loosely packed arrangement, and wax vapour matches the widely spaced arrangement.

> Common mistake: Confusing liquid wax near the wick with gaseous wax.

### Question 9

*3 marks · Short answer*

Why does the water in the ocean taste salty, even though the salt is not visible? Explain.

**Solution**

1. State that salt consists of extremely small constituent particles that are soluble in water.
2. Explain that when salt dissolves, it breaks up into its constituent particles which occupy the interparticle spaces between water particles.
3. Conclude that since these particles are too small to be seen individually even through a microscope, the salt is invisible, but its presence is tasted.

**Answer:** Salt breaks down into constituent particles that spread uniformly and occupy the spaces between water particles, remaining invisible yet present in solution.

> Common mistake: Stating that salt disappears completely without mentioning that it breaks into invisible constituent particles.

### Question 10

*3 marks · Short answer*

Grains of rice and rice flour take the shape of the container when placed in different jars. Are they solids or liquids? Explain.

**Solution**

1. State that both grains of rice and rice flour are solids.
2. Explain that each individual grain of rice or tiny speck of rice flour has a fixed shape, fixed volume, and cannot flow on its own like a liquid.
3. Conclude that they take the shape of the jar only because they are small solid pieces that fill the empty spaces between one another to take the container's shape.

**Answer:** They are solids because each individual grain or particle has a fixed shape and volume, and they only take the shape of the jar collectively.

> Common mistake: Concluding that rice flour is a liquid because it takes the shape of the container.

## Frequently asked questions

### How many questions are there in NCERT Solutions for Class 8 Science Chapter 7 Particulate Nature of Matter?

The chapter includes various sections with a specific number of questions, such as 5 questions in Probe and ponder, 2 questions in Activity 7.1, and 10 questions in Keep the curiosity alive. SwaVid provides complete step-by-step solutions for all these exercises on this page.

### Which topics do the questions in this Class 8 Science chapter cover?

The questions cover essential concepts like the particulate nature of matter, states of matter, interparticle attraction, and properties of liquids and gases. You will also explore activities on the dissolution of sugar, compressibility of gases, and diffusion of potassium permanganate.

### What is the hardest question type in this chapter and how do I approach it?

Long answer and case-based questions in the Keep the curiosity alive section are often considered the most challenging because they test deep conceptual understanding of particle arrangement and behavior. To approach them, break down the scientific reasoning step by step and relate macroscopic observations to microscopic particle properties.

### How can I write answers to get full marks in Class 8 Science exams?

To secure full marks, structure your answers clearly by defining key scientific terms, mentioning relevant activity observations, and using proper terminology related to interparticle spaces and forces. Referring to SwaVid's well-structured solutions on this page will help you learn the exact format expected by examiners.

### Is the free PDF for this Class 8 Science Chapter 7 available?

Yes, the free PDF containing detailed NCERT solutions for the new NCERT book and the 2026-27 session is available right here on this SwaVid page. You can easily download and view it to support your exam preparation without any hassle.

## Related pages

- [Exercise 7.1 solutions](https://www.swavid.com/science/class/8/chapter/particulate-nature-of-matter/ncert-solutions/exercise-7-1)
- [Exercise 7.2 solutions](https://www.swavid.com/science/class/8/chapter/particulate-nature-of-matter/ncert-solutions/exercise-7-2)
- [Exercise 7.3 solutions](https://www.swavid.com/science/class/8/chapter/particulate-nature-of-matter/ncert-solutions/exercise-7-3)
- [Exercise 7.4 solutions](https://www.swavid.com/science/class/8/chapter/particulate-nature-of-matter/ncert-solutions/exercise-7-4)
- [Exercise 7.6 solutions](https://www.swavid.com/science/class/8/chapter/particulate-nature-of-matter/ncert-solutions/exercise-7-6)
- [Exercise 7.7 solutions](https://www.swavid.com/science/class/8/chapter/particulate-nature-of-matter/ncert-solutions/exercise-7-7)
- [Exercise 7.8 solutions](https://www.swavid.com/science/class/8/chapter/particulate-nature-of-matter/ncert-solutions/exercise-7-8)
- [Exercise 7.9 solutions](https://www.swavid.com/science/class/8/chapter/particulate-nature-of-matter/ncert-solutions/exercise-7-9)
- [Class 8 Science chapters](https://www.swavid.com/science/class/8)

Solutions written by SwaVid, a personal AI tutor for Class 6 to 10 Maths and Science. Practise this chapter free: https://www.swavid.com/start/student