Important Questions and Answers for Class 8 Science Chapter 7 Particulate Nature Of Matter 2025-26

1. Multiple choice questions.

1. In which state of matter are the constituent particles packed most closely together?

• (a) Liquid
• (b) Gas
• (c) Solid
• (d) Plasma

Answer: (c) Solid.

2. When sugar dissolves in water, where do the sugar particles go?

• (a) They float on the surface
• (b) They remain undissolved at the bottom
• (c) They occupy spaces between water particles
• (d) They change into a different substance

Answer: (c) They occupy spaces between water particles.

3. Which process shows that matter is made up of tiny particles?

• (a) Melting of ice
• (b) Grinding chalk into powder
• (c) Freezing of water
• (d) Heating iron nail

Answer: (b) Grinding chalk into powder.

4. The property that allows gases to fill the entire available space is due to:

• (a) Minimum movement of particles
• (b) Strong interparticle attraction
• (c) Large interparticle spacing and free movement
• (d) Definite volume

Answer: (c) Large interparticle spacing and free movement.

2. Very Short Answer (VSA).

1. What is meant by constituent particles of matter?

Answer: Constituent particles are the basic tiny units that make up any matter, like atoms or molecules, which cannot be divided further by physical means.

2. State one reason why solids have a fixed shape.

Answer: Solids have a fixed shape because their particles are tightly packed and held together by strong interparticle forces.

3. Name the force which holds constituent particles of matter together.

Answer: Constituent particles of matter are held together by interparticle attractions.

4. Define melting point.

Answer: Melting point is the minimum temperature at which a solid changes to a liquid at atmospheric pressure.

5. Give one example of a process showing water particles are in constant motion.

Answer: When potassium permanganate is added to water, its color spreads, showing that water particles are moving constantly.

3. Short Answer Questions.

1. Why does sand not dissolve in water whereas sugar does?

Answer: Sugar particles are small enough to fit into the spaces between water particles and dissolve. Sand particles are much larger and cannot fit into these spaces, so sand remains undissolved and settles at the bottom.

2. Explain how heating affects the intermolecular forces and state of matter, using the example of melting ice.

Answer: On heating, the thermal energy of ice increases, causing particles to vibrate more energetically. This weakens intermolecular forces, so the solid turns into a liquid as particles move out of their fixed positions.

3. Describe an activity to show that gases have large interparticle spaces.

Answer: In a syringe filled with air, when the plunger is pushed, air volume reduces. This shows gas particles have large spaces between them, as the air can be compressed by bringing the particles closer together.

4. State two differences between solids and gases based on the arrangement and movement of particles.

Answer: In solids, particles are tightly packed and only vibrate in place, resulting in fixed shape and volume. In gases, particles are far apart, move freely in all directions, and do not have fixed shape or volume.

5. Glycerin takes the shape of its container, but iron nails do not. Why?

Answer: Glycerin is a liquid, so its particles are loosely packed and mobile, allowing it to take the shape of a container. Iron nails are solid, with fixed, tightly packed particles, so they retain their shape.

4. True or False Questions.

1. Solids can be compressed easily because their particles have large interparticle spaces.

Answer: False.

2. Evaporation happens at all temperatures, not just at the boiling point.

Answer: True.

3. Liquids have definite volume but no definite shape.

Answer: True.

4. Particles of a gas are so close to each other that they cannot move freely.

Answer: False.

3. Fill in the Blanks Questions.

1. The space between particles is known as _________.

Answer: interparticle space.

2. The temperature at which a liquid changes to a gas is called its ________.

Answer: boiling point.

3. Solids have ________ shape and ________ volume.

Answer: definite; definite.

4. In liquids, the interparticle attractions are ________ compared to solids.

Answer: slightly weaker.

5. Air fills the entire space of a vessel because its particles are ________ and move in ________ directions.

Answer: far apart; all.

Benefits of Understanding Particulate Nature of Matter for Students

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