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STUDYNEST · CLASS 11 PHYSICS

QUESTION PAPER 1

Chapter 12: Kinetic Theory

Original chapter-specific practice paper

Maximum Marks: 40Suggested time: 60 minutes
Instructions: Answer all 20 questions. Marks are shown in brackets. Show calculation steps and units. These are original practice questions, not an official examination paper.

Section A · 1-mark questions — 8 × 1 = 8 marks

  1. What is an ideal gas model?[1]
  2. Ideal gas equation?[1]
  3. Mean translational kinetic energy?[1]
  4. Origin of gas pressure?[1]
  5. Monatomic degrees of freedom?[1]
  6. Effect of lowering pressure on mean free path?[1]
  7. Molar C_v of monatomic gas?[1]
  8. Rms speed relation?[1]

Section B · 2-mark questions — 6 × 2 = 12 marks

  1. At fixed T, volume halves: pressure?[2]
  2. 27°C in Kelvin?[2]
  3. Mean kinetic energy at 300K, k=1.38×10⁻²³?[2]
  4. Temperature becomes 4T: rms speed factor?[2]
  5. Internal energy of n mol monatomic gas?[2]
  6. Two main ideal gas assumptions?[2]

Section C · 3-mark questions — 4 × 3 = 12 marks

  1. Rms speed of M=.028,T=300K,R=8.31?[3]
  2. 1 mol monatomic gas warms 20K, C_v=3R/2: ΔU?[3]
  3. At fixed T, pressure triples: volume factor?[3]
  4. State equipartition prediction for monatomic gas.[3]

Section D · 4-mark questions — 2 × 4 = 8 marks

  1. Compare rms speeds for molar masses .004 and .016 kg/mol at same T.[4]
  2. f=5, n=2 mol, T=300K: internal energy?[4]

End of paper — review signs, units and working.

Open marking scheme and model answers

Attempt the paper before opening the key. Model answers show the expected facts and results; mark allocation is a suggested guide and equivalent correct methods should receive credit.

Q1 · 1 mark
Negligible molecular volume and forces except during elastic collisions.
1 mark for the correct fact, unit or formula. Accept an equivalent correct method.
Q2 · 1 mark
pV=nRT.
1 mark for the correct fact, unit or formula. Accept an equivalent correct method.
Q3 · 1 mark
3k_BT/2.
1 mark for the correct fact, unit or formula. Accept an equivalent correct method.
Q4 · 1 mark
Molecular momentum transfer to walls.
1 mark for the correct fact, unit or formula. Accept an equivalent correct method.
Q5 · 1 mark
Three translational.
1 mark for the correct fact, unit or formula. Accept an equivalent correct method.
Q6 · 1 mark
It increases.
1 mark for the correct fact, unit or formula. Accept an equivalent correct method.
Q7 · 1 mark
3R/2.
1 mark for the correct fact, unit or formula. Accept an equivalent correct method.
Q8 · 1 mark
√(3RT/M).
1 mark for the correct fact, unit or formula. Accept an equivalent correct method.
Q9 · 2 marks
Doubles.
Suggested split: 1 mark for the principle/formula and 1 for the answer or explanation. Accept an equivalent correct method.
Q10 · 2 marks
About 300 K.
Suggested split: 1 mark for the principle/formula and 1 for the answer or explanation. Accept an equivalent correct method.
Q11 · 2 marks
≈6.21×10⁻²¹ J.
Suggested split: 1 mark for the principle/formula and 1 for the answer or explanation. Accept an equivalent correct method.
Q12 · 2 marks
2.
Suggested split: 1 mark for the principle/formula and 1 for the answer or explanation. Accept an equivalent correct method.
Q13 · 2 marks
3nRT/2.
Suggested split: 1 mark for the principle/formula and 1 for the answer or explanation. Accept an equivalent correct method.
Q14 · 2 marks
Negligible particle volume and negligible intermolecular forces except collisions.
Suggested split: 1 mark for the principle/formula and 1 for the answer or explanation. Accept an equivalent correct method.
Q15 · 3 marks
≈517 m/s.
Suggested split: 1 for the relation, 1 for working/reasoning and 1 for result with unit. Accept an equivalent correct method.
Q16 · 3 marks
≈249 J.
Suggested split: 1 for the relation, 1 for working/reasoning and 1 for result with unit. Accept an equivalent correct method.
Q17 · 3 marks
One-third.
Suggested split: 1 for the relation, 1 for working/reasoning and 1 for result with unit. Accept an equivalent correct method.
Q18 · 3 marks
Three translational modes contribute 3k_BT/2 per molecule.
Suggested split: 1 for the relation, 1 for working/reasoning and 1 for result with unit. Accept an equivalent correct method.
Q19 · 4 marks
Lighter gas speed is twice as high.
Suggested split: 1 for principle, 1 for equation, 1 for working and 1 for result/explanation. Accept an equivalent correct method.
Q20 · 4 marks
U=(5/2)nRT=(5/2)(2)(8.31)(300)≈24.9 kJ.
Suggested split: 1 for principle, 1 for equation, 1 for working and 1 for result/explanation. Accept an equivalent correct method.