Class 8 Science Chapter 7 Particulate Nature of Matter Solutions | Curiosity NCERT Answers

 

 

🌟 Class 8 Science – Curiosity Chapter 7

🔬 Particulate Nature of Matter (पदार्थ का कणीय स्वरूप)

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🟢 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.

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✅ Answer:

👉 Correct option is (iv) closely packed in solids and move past each other in liquids.

🧠 Explanation:

• 🧱 Solids (ठोस) → particles tightly packed + fixed position
• 💧 Liquids (द्रव) → particles close but can slide (फिसलना) past each other

🎓 Example:

• 👨‍🎓 Solid = students sitting on fixed benches
• 🏃 Liquid = students moving freely during break

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🟢 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.

(ii) Melting process involves a decrease in interparticle attractions during the transformation.

(iii) Solids have a fixed shape and a fixed volume.

(iv) The interparticle interactions in solids are very strong, and the interparticle 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 heating, we are adding energy to the camphor and the energy is released as a smell.

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✅ Answers:

✔️ (i) True

👉 Melting = solid → liquid (ठोस से द्रव में परिवर्तन)

✔️ (ii) True

👉 Heat energy weakens interparticle forces (कणों के बीच आकर्षण बल)

✔️ (iii) True

👉 Solids have:

• 📏 Fixed shape
• 📦 Fixed volume

✔️ (iv) True

👉 Strong forces + small spaces = rigid structure 💪

✔️ (v) True

👉 Camphor turns into gas → spreads everywhere 🌬️

❌ (vi) False

✏️ Correct Statement:

👉 Heating camphor gives energy → it changes into gas

👉 Gas particles spread in air → reach our nose 👃 → we smell it

⚠️ Energy is not released as smell, it helps in change of state.

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🟢 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.

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✅ Answer:

👉 Correct option is (iii) Nothing of the chair will remain.

🧠 Explanation:

• Chair = made of particles 🧱
• If particles are removed → chair itself disappears ❌

💡 Matter is not a container of particles, it is particles itself.

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🟢 4. Why do gases mix easily, while solids do not?

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✅ Answer:

🌬️ Gases (गैसें):

• Particles far apart
• Very weak forces
• High speed movement 🚀
  👉 Easily mix with each other

🧱 Solids (ठोस):

• Particles tightly packed
• Strong forces 💪
• Fixed positions
  👉 Cannot move → cannot mix

📌 Conclusion:

👉 Freedom of movement = mixing ability

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🟢 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.

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✅ Answer:

🥛 Milk (Liquid):

• Particles close but can move (गतिशील)
• Weak forces
  👉 Flows and spreads easily

🥤 Glass Tumbler (Solid):

• Particles tightly packed
• Strong forces 💪
  👉 Fixed shape → does not flow

📌 Conclusion:

👉 Liquids flow, solids maintain shape

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