Selected MCQ

Current Question
For an ideal gas undergoing adiabatic free expansion into vacuum, the temperature change is:
  • A. Always increases
  • B. Always decreases
  • C. Remains unchanged
  • D. Depends only on volume ratio, not gas type
Correct Answer: C
Explanation:
For an ideal gas, internal energy depends only on temperature and does not change in free expansion.
Related Question 1
Which gas deviates most from ideal behavior at high pressure and low temperature?
  • A. One with negligible intermolecular attraction and molecular volume
  • B. One with significant intermolecular attractions and finite molecular volume
  • C. A hypothetical point-particle gas
  • D. Any gas behaves ideally under all conditions
Correct Answer: B
Explanation:
Real-gas deviations become strong when attractions and excluded volume matter.
Related Question 2
Which atmospheric layer has lowest temperature?
  • A. Troposphere
  • B. Stratosphere
  • C. Mesosphere
  • D. Thermosphere
Correct Answer: C
Explanation:
Mesosphere is coldest.
Related Question 3
The partition function (Z) is related to Helmholtz free energy (F) by:
  • A. (F = kT \ln Z)
  • B. (F = -kT \ln Z)
  • C. (F = Z/kT)
  • D. (F = k/Z)
Correct Answer: B
Explanation:
Helmholtz free energy derives from partition function logarithm.
Related Question 4
Which wave travels in vacuum?
  • A. Sound
  • B. Water
  • C. Light
  • D. Seismic
Correct Answer: C
Explanation:
Light does not require medium.
Related Question 5
Which thermodynamic quantity remains constant in adiabatic process?
  • A. Temperature
  • B. Pressure
  • C. Entropy (reversible case)
  • D. Volume
Correct Answer: C
Explanation:
Reversible adiabatic process is isentropic.