NCERT Solutions for Class 8 Science Chapter 7 - Particulate Nature of Matter

NCERT Solutions for Class 8 Science Chapter 7: Download PDF

Students can download the NCERT Solutions for Class 8 Science Chapter 7 Particulate Nature of Matter exercise questions PDF from the icon given below. These Solutions are designed to help you understand the fundamental concepts and solve textbook questions with ease.

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NCERT Solutions for Class 8 Science Chapter 7 ( Exercise Questions with Answers)

Find accurate and detailed chapter-end questions solutions given in the NCERT textbook. Students can also download the Class 8 Science Chapter 7 PDF.

Keep The Curiosity Alive

Question 1. Choose the correct option. The primary difference between solids and liquids is that the constituent particles are:

(i) Closely packed in solids, while they are stationary in liquids.

(ii) Far apart in solids and have fixed positions in liquids.

(iii) Always moving in solids and have a fixed position in liquids.

(iv) Closely packed in solids and move past each other in liquids.

Answer:

The primary difference between solids and liquids is:

Solid particles are always in a close-packed shape and cannot move freely, while liquids are close together and move past each other, allowing liquids to flow freely.

Hence, the correct answer is option (iv).

Question 2. 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) The 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.

Answer:

(i) True: The process of ice turning into water is an example of a solid changing into a liquid, as ice in its solid state melts to become liquid water.

(ii) True: The attraction between particles decreases during melting. As the solid is heated, its particles absorb energy and vibrate more frequently, which allows them to move more freely and transition into the liquid state.

(iii) True: Due to a closed-packed shape, Solids have a fixed shape and a fixed volume, which is a defining property of solids.

(iv) True: Fixed shape and fixed volume are defining properties of solids. That’s why the interparticle interactions in solids are very strong, and the interparticle spaces are very small.

(v) False:

Correct statement: Camphor undergoes sublimation, which means it directly changes from a solid to a gas. These gas particles then diffuse through the air and carry the smell to all parts of the room. Therefore, the spreading of fragrance is not only because of heating.

(v) False:

Correct statement: The smell doesn’t come from energy being released. Camphor undergoes sublimation, which means it directly changes from a solid to a gas. The vaporized particles of camphor disperse into the air, and these particles produce the fragrance, not the energy itself.

Question 3. Choose the correct answer with justification. If we could remove all the constituent particles from a chair, what would happen?

(i) Nothing will change.

(ii) The chair will weigh less due to lost particles.

(iii) Nothing of the chair will remain

Answer:

A chair is made up of tiny particles such as atoms and molecules. If all of these particles were removed, then there would be no matter left, and the chair would completely disappear. Removing all the constituent particles would leave nothing behind.

Hence, the correct answer is option (iii).

Question 4. Why do gases mix easily, while solids do not?

Answer:

Gases mix easily because they are completely free to move in all directions, which allows gas particles to occupy any available space and makes them mix with other particles easily. While solids have a tightly packed shape and strong intermolecular forces, they can vibrate but can not move freely. That’s why they do not mix easily.

Question 5. 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.

Answer:

Milk is a liquid; it follows the properties of a liquid. As we know, liquids have a loosely packed shape and are also completely free to move, which allows them to flow. That’s why milk spreads when spilled.

A glass tumbler is a solid; it follows the properties of a solid. As we know, solids have a tightly-packed shape and strong intermolecular forces, and they are not free to move, which does not allow them to flow, resulting in solids having a fixed shape and volume; therefore, they always stay in the same shape.

Question 6. Represent diagrammatically the changes in the arrangement of particles as ice melts and transforms into water vapor.

Answer:

The changes in the arrangement of particles as ice melts and transforms into water vapor:

Question 7. Draw a picture representing particles present in the following:

(i) Aluminium foil

(ii) Glycerin

(iii) Methane gas

Answer:

(i) A picture representing particles present in the Aluminium foil: It is a solid, so it will have a solid-like particle arrangement (regular pattern and close together), which is given below.

(ii) A picture representing particles present in the glycerin: It is a liquid, so it will have a liquid-like particle arrangement (irregular pattern and close together) , which is given below.

(ii) A picture representing particles present in the methane gas: It is a gas, so it will have a gas-like particle arrangement (irregular pattern and far apart), which is given below.

Question 8. Observe Fig. 7.16(a), 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. 7.16(b), showing the arrangement of particles.

Answer:

Different states of wax:

Solid wax: Unmelted part of the candle

Arrangements of particles in solid wax:

Liquid wax: Near the wick, heat from the flame melts the solid wax into a liquid.

Arrangements of particles in liquid wax:

Vapour wax (Gas): When the candle is burning, due to the high temperature near the flame, some of the liquid wax vaporizes.

Arrangements of particles in vapour wax:

Question 9. Why does the water in the ocean taste salty, even though the salt is not visible? Explain.

Answer:

Ocean water has a salty taste because it contains various dissolved salts, mainly sodium chloride (NaCl). These salts are released from rocks through natural processes. Rainwater dissolves the minerals from rocks, and rivers carry them into the ocean, where the salts have been collecting for millions of years. It is fully dissolved in the water. At the molecular level, it breaks down into tiny sodium and chloride ions, which can not be seen with the naked eye.

Question 10. Grains of rice and rice flour take the shape of the container when placed in different jars. Are they solids or liquids? Explain.

Answer:

Grains of rice and rice flour are solids that have a fixed shape and volume. They do not flow freely like a liquid at the particle level (defining property of solids). However, when large numbers of these solid particles are poured into a container, they settle and spread out, making it look like they are taking the shape of the container, but this is due to their small size and loose arrangement, not because they are liquids.

Approach to Solve the Question of Class 8 Science Chapter 7

Sometimes Class 8 Science Chapter 7 NCERT Solutions seem very difficult, but once we understand the basic rules and strategy, it becomes very easy to solve all the questions related to that particular topic. We can follow the steps given below to solve exercise questions effectively.

1. Understand the key Concepts first

Before attempting questions, make sure you clearly know the topics, like What are solids, liquids, and gases? The differences between them e.g., defining properties, phase change methods, etc and the types of phase change methods, such as melting, boiling, sublimation, evaporation, etc.

2. Identify the keywords in the question

Look for words like particle arrangement, structure, shape, solids, liquids, gases, different properties, phase change methods, etc., as they will help you decide whether it is a solid, liquid or gas. You can learn these concepts from the NCERT solutions for Class 8 Science Chapter 7 Particulate Nature of Matter.

3. Make notes

You can use a table to classify the solids, liquids, and gases. This will help you a lot in answering the questions. Also, learn the difference between the phase change methods, such as sublimation, condensation, evaporation, etc

4. Practice equations

Practice as many questions as asked in previous board exams and solve mock tests. Also, solve all the questions given in the NCERT solution for Class 8 Science Chapter 7 Particulate Nature of Matter to score well in exams.

5. Understand the activities

The activities discussed in this chapter are so important and are often asked in exams. Do practice them attentively. Also, focus on true-false and explanation-based questions as they are crucial to understanding.

Topic Covered in Class 8 Chapter 7: Particulate Nature of Matter

Given below the topics and subtopics covered in Chapter 7 Particulate Nature of Matter. Students can also refer to the NCERT textbook for a complete understanding of all the topics.

7.1 What Is Matter Composed of?

7.2 What Decides Different States of Matter?

• 7.2.1 Solid state
• 7.2.2 Liquid state
• 7.2.3 Gaseous state

7.3 How Does the Interparticle Spacing Differ in the Three States of Matter?

7.4 How Particles Move in Different States of Matter?

NCERT Chapter-Wise Solutions For Class 8 Science

Besides NCERT solutions for Class 8 Science Chapter 7 Particulate Nature of Matter, chapter-wise solutions are given below:

NCERT Solutions For Class 8 Subject-Wise

NCERT Subject-wise solutions for class 8 are given below:

NCERT Books and NCERT Syllabus

The NCERT books and syllabus links for class 8 are given below: