🔥 Kinetic Theory of Gases – Stage 3 (Page 4)

Extreme Level Problems (IIT-JEE Advanced)

This page blends thermodynamics + mechanics + statistics. Only conceptual clarity survives here.

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🔹 Question 1 (Microscopic vs Macroscopic)

A gas is enclosed in a container. One molecule suddenly doubles its speed. Which quantity of the gas changes immediately?

• A) Temperature
• B) Pressure
• C) Internal energy
• D) None

Correct Answer: D

Explanation:
Macroscopic quantities depend on huge number of molecules, not a single one.

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🔹 Question 2 (Very Tricky – RMS Speed)

At constant pressure, temperature of gas is doubled. RMS speed changes by:

• A) √2
• B) 2
• C) 1/√2
• D) Remains same

Correct Answer: A

Why?
v_rms ∝ √T (independent of pressure).

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🔹 Question 3 (Pressure–Velocity Relation)

If average speed of gas molecules is increased by 20%, pressure at constant volume changes by:

Solution:

• Pressure ∝ v²
• New pressure = (1.2)² = 1.44

Answer: Increases by 44%

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🔹 Question 4 (Collision Frequency)

Which change increases collision frequency the most?

• A) Increase temperature
• B) Decrease volume
• C) Increase molecular diameter
• D) All of the above

Correct Answer: D

Concept:
Collision frequency ∝ nσv

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🔹 Question 5 (Work Done Trap)

A gas expands freely into vacuum. What is the change in temperature?

• A) Increases
• B) Decreases
• C) Remains same
• D) Cannot be predicted

Correct Answer: C

Reason:
No work done, no heat exchange → ΔU = 0

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🔹 Question 6 (Speed Distribution Logic)

Which speed is maximum in magnitude?

• A) Most probable speed
• B) Average speed
• C) RMS speed
• D) All equal

Correct Answer: C

Order:
v_mp < v_avg < v_rms

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🧠 IIT Examiner Psychological Traps

• One molecule does not define temperature
• Speed squared controls pressure
• Free expansion ≠ cooling

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✅ Stage 3 – Page 4 Completed

📚 IIT–JEE Physics Complete Library (Class XI)

Curated for IIT-JEE Advanced Aspirants
Concepts • Numericals • Objective Questions • Revision Capsules

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🔥 Kinetic Theory of Gases (KTG) – Complete Library

1. KTG – Part 1
2. KTG – Part 2
3. KTG – Part 3
4. KTG – Part 4
5. KTG – Part 5
6. KTG – Part 6
7. KTG – Part 7
8. KTG – Special Notes
9. KTG – Part 9
10. KTG – Part 10
11. KTG – Part 11
12. KTG – Part 12
13. KTG – Part 13
14. KTG – Part 14
15. KTG – Part 15
16. KTG – Part 16
17. KTG – Part 17
18. KTG – Part 18
19. KTG – Part 19
20. KTG – Part 20
21. KTG – Part 21
22. KTG – Part 22
23. KTG – Part 23
24. KTG – Part 24
25. KTG – Part 25
26. KTG – Part 26
27. KTG – Part 27
28. KTG – Part 28
29. KTG – Part 29
30. KTG – Part 30

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📐 Properties of Matter – Complete IIT-JEE Library

1. Properties – Part 1
2. Properties – Part 2
3. Properties – Part 3
4. Properties – Part 4
5. Properties – Part 5
6. Properties – Part 6
7. Properties – Part 7
8. Properties – Part 8
9. Properties – Part 9
10. Properties – Part 10
11. Properties – Part 11
12. Properties – Part 12
13. Properties – Part 13
14. Properties – Part 14
15. Properties – Part 15
16. Properties – Part 16
17. Properties – Part 17
18. Properties – Part 18
19. Properties – Part 19
20. Properties – Part 20
21. Properties – Part 21
22. Properties – Part 22
23. Properties – Part 23
24. Properties – Part 24
25. Properties – Part 25

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🌟 Master & Mega Physics Libraries

• IIT-JEE Physics Master Library
• Physics Complete Mega Library
• SHM Complete Library
• Waves – JEE Advanced Library
• Gravitation Library
• Momentum & Collisions Library
• Centre of Mass Library
• Work Energy Power Library

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