PHYSICS-Kinetic Theory of Gases Questions and Answers

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Q1
What is the relationship between pressure and volume of a gas at constant temperature according to Boyle's law?
  • A Directly proportional
  • B Inversely proportional
  • C No relationship
  • D Exponentially related
Answer: Option B
Explanation: Boyle's law states that pressure is inversely proportional to volume when temperature is constant.
Q2
Which of the following is NOT an assumption of the kinetic theory of gases?
  • A Molecules are in random motion
  • B Molecules have negligible volume
  • C Molecules exert no forces on each other
  • D Molecules have zero mass
Answer: Option D
Explanation: Gas molecules do have mass, though very small. The kinetic theory assumes molecules have negligible volume, not zero mass.
Q3
What happens to the average kinetic energy of gas molecules when temperature is doubled?
  • A Doubles
  • B Halves
  • C Quadruples
  • D Remains same
Answer: Option A
Explanation: Average kinetic energy is directly proportional to absolute temperature.
Q4
At constant volume, pressure of a gas is proportional to:
  • A Volume
  • B Temperature
  • C Number of molecules
  • D Density
Answer: Option B
Explanation: Gay-Lussac's law states that pressure is proportional to temperature at constant volume.
Q5
The root mean square speed of gas molecules depends on:
  • A Pressure only
  • B Volume only
  • C Temperature and molecular mass
  • D Pressure and volume
Answer: Option C
Explanation: RMS speed depends on temperature and molecular mass.
Q6
Which gas law combines Boyle's, Charles' and Gay-Lussac's laws?
  • A Avogadro's law
  • B Ideal gas equation
  • C Van der Waals equation
  • D Dalton's law
Answer: Option B
Explanation: Ideal gas equation PV = nRT combines all three gas laws.
Q7
What is the value of universal gas constant R?
  • A 0.0821 L·atm/mol·K
  • B 1.987 cal/mol·K
  • C 8.314 J/mol·K
  • D 62.36 L·torr/mol·K
Answer: Option C
Explanation: R = 8.314 J/mol·K is the standard value.
Q8
At absolute zero temperature, what happens to gas molecules?
  • A They move fastest
  • B Their volume becomes zero
  • C Their motion ceases
  • D They become liquid
Answer: Option C
Explanation: At absolute zero, molecular motion ceases according to kinetic theory.
Q9
The average kinetic energy of gas molecules is directly proportional to:
  • A Volume
  • B Pressure
  • C Absolute temperature
  • D Number of molecules
Answer: Option C
Explanation: KE_avg = (3/2)kT shows direct proportionality to absolute temperature.
Q10
Which of the following has the same RMS speed at same temperature?
  • A O₂ and N₂
  • B H₂ and He
  • C CO₂ and SO₂
  • D N₂ and CO
Answer: Option D
Explanation: RMS speed depends on molecular mass. Same mass means same RMS speed at same temperature.
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