Page 96 - Innovator's Science-8

Points to Reflect
• Matter is anything that has mass and occupies space.
• The particles are held together by interparticle forces of attractions.

• The movement of particles increases with rise in temperature.
• The force of attraction between particles decides whether a substance is solid, liquid, or gas.
• Solids have very little interparticle space, liquids have more, and gases have the most.
• Heating can change the state of matter by increasing particle motion and reducing attraction.
• Ancient Indian philosopher Acharya Kanad first proposed the idea that matter is made of indivisible
particles called Parmanu.

• The spacing between particles increases from solids to liquids to gases, and this explains the different
properties of the three states of matter.

NCERT Textbook Questions (Solved)
Let Us Enhance Our Learning

1. Choose the correct op on.

The primary difference between solids and liquids is that the cons tuent par cles are:
i. closely packed in solids, while they are sta onary in liquids.
ii. far apart in solids and have fixed posi ons in liquids.
iii. always moving in solids and have a fixed posi on in liquids.
iv. closely packed in solids and move past each other in liquids.
Ans. 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. Mel ng ice into water is an example of the transforma on of a solid into a liquid.
ii. The mel ng process involves a decrease in interpar cle a rac ons during the transforma on.
iii. Solids have a fixed shape and a fixed volume.
iv. The interpar cle interac ons in solids are very strong, and the interpar cle 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 hea ng, we are adding energy to the camphor, and the energy is released as a smell.
Ans. i. True, ii. True, iii. True, iv. True, v. True, vi False (The correct statement is : On hea ng energy is added
to camphor, causing it to undergo sublima on. The camphor directly converts into gas, and the vapour
carries its characteris c smell.)

3. Choose the correct answer with jus fica on. If we could remove all the cons tuent par cles from a
chair, what would happen?
i. Nothing will change.
ii. The chair will weigh less due to lost par cles.
iii. Nothing of the chair will remain.
Ans. Correct op on is (iii) Nothing of the chair will remain.
Jus fica on: A chair is made of ny par cles called atoms and molecules. These par cles give the chair
its shape, structure, and weight. If all these par cles are removed, there would be nothing le , and the
chair would no longer exist.

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Science-8