🔥 Kinetic Theory of Gases – Stage 3 (Page 6)
Advanced Assertion–Reason & Multi-Concept Problems
🔹 Question 1 (Assertion–Reason)
Assertion (A): At constant temperature, pressure of a gas depends on the mass of molecules.
Reason (R): Heavier molecules collide with walls with greater momentum.
Correct Option: Assertion is false, Reason is true.
Explanation:
Pressure depends on number density and ⟨KE⟩, not directly on molecular mass.
Momentum per collision is higher for heavier molecules, but collision frequency is lower.
🔹 Question 2 (Mean Free Path)
If pressure of a gas is doubled at constant temperature, mean free path becomes:
- A) Doubled
- B) Halved
- C) Four times
- D) Same
Correct Answer: B
Concept:
Mean free path λ ∝ 1 / pressure
🔹 Question 3 (Collision Frequency)
Which change increases collision frequency per molecule?
- A) Increase temperature
- B) Decrease molecular diameter
- C) Decrease pressure
- D) Increase volume
Correct Answer: A
Reason:
Higher speed → more collisions per second.
🔹 Question 4 (Gas in Gravity Field)
In a vertical column of gas at equilibrium:
- A) Temperature decreases with height
- B) Pressure decreases with height
- C) RMS speed decreases with height
- D) Mean kinetic energy decreases
Correct Answer: B
Key Insight:
Temperature remains constant; only number density changes.
🔹 Question 5 (Energy Transport)
Thermal conductivity of gases mainly depends on:
- A) Density
- B) Pressure
- C) Molecular speed
- D) Volume
Correct Answer: C
Explanation:
Energy transfer occurs due to fast-moving molecules.
🔹 Question 6 (RMS Speed Comparison)
At same temperature, which gas has highest RMS speed?
- A) O₂
- B) N₂
- C) CO₂
- D) H₂
Correct Answer: D
Rule:
vrms ∝ 1 / √m
🔹 Question 7 (Pressure from KTG)
KTG pressure formula is derived assuming:
- A) Elastic collisions
- B) No intermolecular forces
- C) Random motion
- D) All of the above
Correct Answer: D
⚠️ IIT Examiner Mindset (Stage 3)
- Separate temperature vs pressure vs density
- Never mix KE with speed blindly
- Gravity affects pressure, not temperature
🏆 Stage 3 – Page 6 Completed (Elite Level)
📚 IIT–JEE Physics Complete Library (Class XI)
Curated for IIT-JEE Advanced Aspirants
Concepts • Numericals • Objective Questions • Revision Capsules
🔥 Kinetic Theory of Gases (KTG) – Complete Library
- KTG – Part 1
- KTG – Part 2
- KTG – Part 3
- KTG – Part 4
- KTG – Part 5
- KTG – Part 6
- KTG – Part 7
- KTG – Special Notes
- KTG – Part 9
- KTG – Part 10
- KTG – Part 11
- KTG – Part 12
- KTG – Part 13
- KTG – Part 14
- KTG – Part 15
- KTG – Part 16
- KTG – Part 17
- KTG – Part 18
- KTG – Part 19
- KTG – Part 20
- KTG – Part 21
- KTG – Part 22
- KTG – Part 23
- KTG – Part 24
- KTG – Part 25
- KTG – Part 26
- KTG – Part 27
- KTG – Part 28
- KTG – Part 29
- KTG – Part 30
📐 Properties of Matter – Complete IIT-JEE Library
- Properties – Part 1
- Properties – Part 2
- Properties – Part 3
- Properties – Part 4
- Properties – Part 5
- Properties – Part 6
- Properties – Part 7
- Properties – Part 8
- Properties – Part 9
- Properties – Part 10
- Properties – Part 11
- Properties – Part 12
- Properties – Part 13
- Properties – Part 14
- Properties – Part 15
- Properties – Part 16
- Properties – Part 17
- Properties – Part 18
- Properties – Part 19
- Properties – Part 20
- Properties – Part 21
- Properties – Part 22
- Properties – Part 23
- Properties – Part 24
- Properties – Part 25
🌟 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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