PHYSICS-Kinetic Theory of Gases Questions and Answers

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Q11
What is the effect on pressure if number of molecules is doubled at constant volume and temperature?
  • A Halves
  • B Doubles
  • C Quadruples
  • D Remains same
Answer: Option B
Explanation: According to ideal gas law, pressure is directly proportional to number of molecules.
Q12
The constant in Charles' law is:
  • A Pressure
  • B Volume
  • C Volume/Temperature
  • D Pressure/Temperature
Answer: Option C
Explanation: Charles' law: V/T = constant at constant pressure.
Q13
What is the dimensional formula for universal gas constant R?
  • A [MLT⁻²K⁻¹]
  • B [ML²T⁻²K⁻¹mol⁻¹]
  • C [ML⁻¹T⁻²K⁻¹]
  • D [M⁰L⁰T⁰K⁻¹]
Answer: Option B
Explanation: From PV = nRT, R = PV/nT. Dimensions: [ML²T⁻²K⁻¹mol⁻¹].
Q14
Which gas deviates most from ideal behavior at high pressure?
  • A Hydrogen
  • B Oxygen
  • C Carbon dioxide
  • D Helium
Answer: Option C
Explanation: CO₂ deviates significantly due to intermolecular forces and molecular size.
Q15
The mean free path of gas molecules:
  • A Increases with pressure
  • B Decreases with pressure
  • C Independent of pressure
  • D Independent of temperature
Answer: Option B
Explanation: Mean free path is inversely proportional to pressure and collision cross-section.
Q16
According to kinetic theory, pressure exerted by gas is due to:
  • A Gravitational attraction
  • B Molecular collisions with walls
  • C Intermolecular forces
  • D Chemical reactions
Answer: Option B
Explanation: Pressure results from molecular collisions with container walls.
Q17
What is the ratio of most probable speed to RMS speed?
  • A √(2/3)
  • B √(3/2)
  • C 2/3
  • D 3/2
Answer: Option A
Explanation: Most probable speed = √(2RT/M), RMS speed = √(3RT/M). Ratio = √(2/3).
Q18
At same temperature, which gas has highest average speed?
  • A Oxygen
  • B Nitrogen
  • C Hydrogen
  • D Carbon dioxide
Answer: Option C
Explanation: Lighter molecules have higher average speed at same temperature.
Q19
The law of equipartition of energy states that:
  • A Energy depends on molecular size
  • B Energy is quantized
  • C Energy is equally distributed among degrees of freedom
  • D Energy decreases with temperature
Answer: Option C
Explanation: Equipartition theorem: energy is equally distributed among all degrees of freedom.
Q20
What happens to the density of gas when pressure is doubled at constant temperature?
  • A Halves
  • B Doubles
  • C Quadruples
  • D Remains same
Answer: Option B
Explanation: From ideal gas law, density is proportional to pressure at constant temperature.
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