Particulate Nature of Matter Class 8 Science Chapter 7 Questions Answers Looking for the Particulate Nature of Matter Class 8 Science Chapter 7 Questions Answers? You’re in the right place! This chapter explains that matter is made up of tiny particles, how these particles behave, and why different substances have different properties. Understanding these concepts is essential for scoring well in school exams and building a strong science foundation.
Probe and ponder (Page 98)
Q. Why is it possible to pile up stones or sand, but not a liquid like water?
Answer:
Solids, like stones and sand, have a definite shape and volume because their particles are tightly packed and held together by strong forces of attraction. Hence, they can be piled up.
Liquids such as water have weaker forces between their particles and can’t retain a fixed shape. They flow and take the shape of their container, so they cannot be piled up.
Q. Why does water take the shape of folded hands but lose that shape when released?
Answer:
Liquids do not possess a fixed shape; they take the shape of the container in which they are held. Therefore, water takes the shape of folded hands when contained within them, but loses that shape when it is released.
Q. We cannot see air, so how does it add weight to an inflated balloon?
Answer:
Air is made up of tiny particles of gases that have mass and are constantly moving. When air is blown into a balloon, these particles fill the space inside it. Since the air particles have mass, they add weight to the inflated balloon.
Q. Is the air we breathe today the same that existed thousands of years ago?
Answer:
The Earth has had an atmosphere containing gases such as nitrogen, oxygen, and carbon dioxide for millions of years. Therefore, the air we breathe today is part of the same atmosphere that has been circulating and renewing itself over time, and it is the same air that existed thousands of years ago.
Keep the curiosity alive (Page 113 – 114)
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 position in liquids.
(iii) always moving in solids and have fixed position in liquids.
(iv) closely packed in solids and move past each other in liquids.
Answer:
(iv) closely packed in solids and move past each other in liquids.
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.
Answer:
True.
(ii) Melting process involves a decrease in interparticle attractions during the transformation.
Answer:
True.
(iii) Solids have a fixed shape and a fixed volume.
Answer:
True.
(iv) The interparticle interactions in solids are very strong, and the interparticle spaces are very small.
Answer:
True.
(v) When we heat camphor in one corner of a room, the fragrance reaches all corners of the room.
Answer:
True.
(vi) On heating, we are adding energy to the camphor, and the energy is released as a smell.
Answer:
False.
Correct statement: On heating, we are adding energy to the camphor. It undergoes sublimation, changing directly from solid to vapour, and these vapours carry its smell.
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:
(iii) Nothing of the chair will remain.
4. Why do gases mix easily, while solids do not?
Answer:
Gases mix easily because they have large interparticle spaces and very weak forces of attraction between their particles. This allows gas particles to move freely and spread in all directions. In contrast, solids have very little space between particles and strong forces of attraction, so they do not mix easily.
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 in a glass tumbler flows and spreads out because liquids do not have a fixed shape. The particles of a liquid are loosely packed and can move freely due to weak interparticle forces of attraction. The glass tumbler, on the other hand, is a solid. Its particles are tightly packed with strong forces of attraction, which help it retain a definite shape.
6. Represent diagrammatically the changes in the arrangement of particles as ice melts and transforms into water vapour.
Answer:
7. Draw a picture representing particles present in the following:
(i) Aluminium foil
(ii) Glycerin
(iii) Methane gas
Answer:
(i) Aluminium foil
(ii) Glycerin
(iii) Methane gas
8. 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.
Answer:
9. Why does the water in the ocean taste salty, even though the salt is not visible? Explain
Answer:
The water in the ocean tastes salty because it contains dissolved salts, mainly sodium chloride. These salts are not visible because they are dissolved at the molecular level and mix uniformly with the water.
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:
Both grains of rice and rice flour are solids. Each grain or particle has a fixed shape and does not flow like a liquid. They appear to take the shape of the container because the small solid particles move and settle to fill the space.
At School Learners, we provide easy-to-understand NCERT Solutions, important questions, detailed explanations, MCQs, worksheets, and exam preparation material for Class 8 Science. Our solutions are written in simple language so that every student can learn quickly and confidently.
Read the complete Particulate Nature of Matter Class 8 Science Chapter 7 Questions Answers here: https://schoollearners.in/
Visit School Learners for the latest NCERT solutions, study notes, previous year questions, and free learning resources to boost your exam preparation. Whether you’re revising before an exam or learning a topic for the first time, schoollearners.in/ is your trusted learning partner.