Question 1

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? (Page 99)

Accepted Answer

Yes, even after breaking or grinding, each speck of chalk powder (fine-grinded) is the same as the previous state because this change is a physical change in which only the size of chalk changes, not any chemical change occurred.

Question 2

Are the units of chalk obtained in this manner considered the smallest units of chalk? (Page 100)

Accepted Answer

No, the obtained units of chalk in the process of grinding are not the smallest unit. Every unit of chalk is even consists of constituent particles, which are the basic units of chalk.

Source: This question is from Particulate Nature of Matter, Science &mdash; Class 8, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Particulate Nature of Matter: Units, Chalk, Obtained, Manner, Considered, Smallest. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 8 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberRead the question carefully and identify all parts before answering.
Use the terminology specific to this subject and chapter.
Review the textbook content for this chapter before attempting questions.
Practice writing concise, well-structured answers within time limits.
Related Questions from Particulate Nature of MatterQ1: Is every speck of this fine chalk powder still composed of the same substance, or has it changed...
Q10: Grains of rice and rice flour take the shape of the container when placed in different jars. Are...
Q3: Do gases also have a fixed volume? (Page 105)
Q4: Sugar and sand are both solids. Why does sugar dissolve in water, but sand does not? (Page 108)
Q5: When spilled on the table, milk in a glass tumbler flows and spreads out, but the glass tumbler...
Practice more questions from Particulate Nature of Matter &mdash; Science, Class 8 CBSE

Question 3

Do gases also have a fixed volume? (Page 105)

Accepted Answer

No, gases don’t have a fixed shape or volume. The volume of gas changes with the amount of closeness of particles or the interparticle attraction between particles.

Source: This question is from Particulate Nature of Matter, Science &mdash; Class 8, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Particulate Nature of Matter: Gases, Fixed, Volume, Page, Particulate Nature of Matter, Science. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 8 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberRead the question carefully and identify all parts before answering.
Use the terminology specific to this subject and chapter.
Review the textbook content for this chapter before attempting questions.
Practice writing concise, well-structured answers within time limits.
Related Questions from Particulate Nature of MatterQ1: Is every speck of this fine chalk powder still composed of the same substance, or has it changed...
Q10: Grains of rice and rice flour take the shape of the container when placed in different jars. Are...
Q4: Sugar and sand are both solids. Why does sugar dissolve in water, but sand does not? (Page 108)
Q5: When spilled on the table, milk in a glass tumbler flows and spreads out, but the glass tumbler...
Q6: Represent diagrammatically the changes in the arrangement of particles as ice melts and transforms...
Practice more questions from Particulate Nature of Matter &mdash; Science, Class 8 CBSE

Question 4

Sugar and sand are both solids. Why does sugar dissolve in water, but sand does not? (Page 108)

Accepted Answer

Sugar particles are solid, but they dissolve in water and occupy some space between the water molecules. Because water can break down sugar particles, which reduces the total volume of the mixture. Whereas sand particles have a rigid crystal structure, which cannot be broken down by water molecules, and hence settle down in water and increasing the total volume.
NCERT Class 8 Science Chapter 7 Question Answer Particulate Nature of Matter (Exercise)
Keep the Curiosity Alive (Pages 113-114)

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.

Accepted Answer

In this case, milk is spilled on the table, and it spreads around the table because its state is liquid. Liquids can take the shape of their surrounding because their molecules are free to move. This is the reason the milk flows around the table. Whereas the glass tumbler’s shape does not change because it is a solid. In solids, the molecules are closely packed.

Question 6

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

Accepted Answer

As ice melts into water and then vaporizes into steam, the arrangement of water particles changes significantly. Initially, in ice (a solid), water molecules are tightly packed in a fixed, crystalline structure with limited movement (vibrations). As ice melts, the particles gain kinetic energy, breaking free from their fixed positions and becoming able to slide past each other, forming liquid water. Further heating increases the kinetic energy, causing the particles to move more rapidly and spread out, eventually breaking free from the liquid and becoming water vapour, a gas with particles moving randomly and freely.
Ice (Solid)
Arrangement: Water molecules are tightly packed in a regular, crystalline structure.
Movement: Molecules vibrate in fixed positions.
Liquid Water
Arrangement: Molecules are closer together than in a gas, but not in a regular structure. They can move around and slide past each other.
Movement: Molecules can move around and slide past each other.
Water Vapor (Gas)
Arrangement: Molecules are far apart and move randomly and freely in all directions.
Movement: Molecules move rapidly and randomly, colliding with each other and the container walls.

Question 7

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

Accepted Answer

Pictorial representation of particles of Aluminium foil, Glycerin, and Methane gas.

Source: This question is from Particulate Nature of Matter, Science &mdash; Class 8, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Particulate Nature of Matter: Picture, Representing, Particles, Present, Aluminium, Foil. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 8 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberRead the question carefully and identify all parts before answering.
Use the terminology specific to this subject and chapter.
Review the textbook content for this chapter before attempting questions.
Practice writing concise, well-structured answers within time limits.
Related Questions from Particulate Nature of MatterQ1: Is every speck of this fine chalk powder still composed of the same substance, or has it changed...
Q10: Grains of rice and rice flour take the shape of the container when placed in different jars. Are...
Q3: Do gases also have a fixed volume? (Page 105)
Q4: Sugar and sand are both solids. Why does sugar dissolve in water, but sand does not? (Page 108)
Q5: When spilled on the table, milk in a glass tumbler flows and spreads out, but the glass tumbler...
Practice more questions from Particulate Nature of Matter &mdash; Science, Class 8 CBSE

Question 8

Observe figure (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 figure B, showing the arrangement of particles.

Accepted Answer

Different states of wax

Source: This question is from Particulate Nature of Matter, Science &mdash; Class 8, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Particulate Nature of Matter: Observe, Figure, Shows, Image, Candle, Extinguished. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 8 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberRead the question carefully and identify all parts before answering.
Use the terminology specific to this subject and chapter.
Review the textbook content for this chapter before attempting questions.
Practice writing concise, well-structured answers within time limits.
Related Questions from Particulate Nature of MatterQ1: Is every speck of this fine chalk powder still composed of the same substance, or has it changed...
Q10: Grains of rice and rice flour take the shape of the container when placed in different jars. Are...
Q3: Do gases also have a fixed volume? (Page 105)
Q4: Sugar and sand are both solids. Why does sugar dissolve in water, but sand does not? (Page 108)
Q5: When spilled on the table, milk in a glass tumbler flows and spreads out, but the glass tumbler...
Practice more questions from Particulate Nature of Matter &mdash; Science, Class 8 CBSE

Question 9

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

Accepted Answer

Ocean water tastes salty because it contains a high concentration of dissolved salts, primarily sodium chloride (common table salt). These salts are not visible because they are dissolved at a molecular level, meaning the individual salt molecules are dispersed throughout the water, making it appear clear.

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.

Accepted Answer

Grains of rice and rice flour are considered solids, despite appearing to take the shape of their container. This is because each grain retains its shape and volume, even when mixed. The “flowing” behavior is due to the ability of these small, irregularly shaped particles to move past each other with minimal friction.
Class 8 Particulate Nature of Matter Question Answer (Activities)
Activity 7.9: Let us find out (Page 110)
1. Light an incense stick in one corner of the room.
2. Wait for a few minutes and observe.
3. Do you notice the fragrance from a distance?
Answer:
Observations:
We can smell the fragrance of an incense stick from one corner.
Slowly, the fragrance of this incense stick can be smelled all around the room.
Conclusions:
The smell of an incense stick can be observed throughout the room because the particles of air are moving randomly.
As the interparticle forces are weak, they can move freely around the room.