Particulate Nature of Matter
Short Questions
1. What are constituent particles?
Answer:- Tiny units that make up a substance.
2. Why can’t liquids be piled up like solids?
Answer:- Liquids flow and take the shape of their container.
3.What holds particles together in matter?
Answer:- Interparticle attractions.
4.What is the melting point of a solid?
Answer:- The temperature at which a solid turns into a liquid.
5. Do gases have a fixed shape?
Answer:- No, gases take the shape of their container.
6.What happens to sugar when it dissolves in water?
Answer:- It breaks into tiny particles and mixes with water.
7.Why is water incompressible?
Answer:- Its particles are closely packed with little space.
8. What is the boiling point of a liquid?
Answer:- The temperature at which a liquid turns into a gas.
9.Why do solids have a fixed shape?
Answer:- Strong interparticle attractions hold particles in place.
10.What is evaporation?
Answer:- The slow process where liquid turns into vapor at the surface.
11.Why does smoke spread in a gas jar?
Answer:- Gas particles move freely and fill all available space.
12.What did Acharya Kanad call the smallest unit of matter?
Answer:- Parmanu (atom).
13.Why does potassium permanganate spread faster in hot water?
Answer:- Water particles move faster in hot water.
14.What is interparticle spacing?
Answer:- The space between particles in matter.
15. Why don’t sand particles dissolve in water?
Answer:- Sand particles are held together by strong forces.
Long Questions
1. Why can’t we pile up water like sand or stones?
Answer:- Water is a liquid with weak interparticle forces, so it flows and takes the shape of its container. Sand and stones are solids with strong forces, keeping them in a fixed shape.
2. How does grinding chalk into powder demonstrate a physical change?
Answer:- Grinding chalk reduces its size but doesn’t change its chemical composition. It remains chalk, showing it’s a physical change.
3.Why does water take the shape of folded hands but lose it when released?
Answer:- Water is a liquid, so its particles move to fit the shape of folded hands. When released, weak interparticle forces let it flow freely.
4.How does an inflated balloon show that air has weight?
Answer:- Air particles inside the balloon add mass, making it heavier. This is why an inflated balloon weighs more than an empty one.
5.Why does sugar disappear when dissolved in water, but we can still taste it?
Answer:- Sugar breaks into tiny particles that mix with water particles, becoming invisible. We taste it because these particles are still present in the solution.
6.How do interparticle forces differ in solids, liquids, and gases?
Answer:- Solids have strong interparticle forces, keeping particles fixed; liquids have weaker forces, allowing movement; gases have negligible forces, letting particles move freely. This affects their shape and volume.
7.Why do gases mix easily compared to solids?
Answer:- Gas particles have weak interparticle forces and large spaces, allowing them to mix freely. Solids have strong forces and tightly packed particles, preventing easy mixing.
8.What happens to the particles of a solid when it is heated to its melting point?
Answer:- Heating increases particle vibrations, weakening interparticle forces. This allows particles to move apart, turning the solid into a liquid.
9.Why does the fragrance of an incense stick spread throughout a room?
Answer:- Gas particles from the incense move freely and collide with air particles. This causes the fragrance to spread and fill the entire room.
10.How does the dissolution of sugar in water show interparticle spacing?
Answer:- Sugar particles occupy spaces between water particles when dissolved. This shows that liquids have some interparticle spacing, unlike tightly packed solids.
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