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Kinetic Theory of Gases appeared 26 times across 3 years — 3% of Physics. This question is from Kinetic Energy of Gas Molecules.

Year 2026 2025 2024 Total
Questions 6 11 9 26
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The helium and argon are put in the flask at the same room temperature (300 K). The ratio of average kinetic energies (per molecule) of helium and argon is : (Give: Molar mass of helium = 4 g/mol, Molar mass of argon =40~g/mol) [cite: 74, 75, 76, 77]

Solution & Explanation

Related Formula

K.E. = (f)/(2) kB T [cite: 688]

Core Logic

The average kinetic energy per molecule depends only on the temperature T and the degrees of freedom f of the gas[cite: 75, 688]. Both Helium (He) and Argon (Ar) are monoatomic noble gases, meaning both share the same degrees of freedom (f = 3)[cite: 689]. Since they sit in the same flask at identical room temperature (T = 300 K), their translational kinetic energies per molecule are exactly equal [cite: 74, 688]:

K.E.HeK.E.Ar = (1)/(1) [cite: 688]

Pattern Recognition

Do not get distracted by the molar masses given in the question stem[cite: 76, 77]. Kinetic energy per molecule is purely temperature-dependent for an ideal gas, unlike the root-mean-square velocity (vrms) which explicitly includes molecular weight.

Chapter Mix

Class 11 Physics: Kinetic Theory of Gases

Reference Study Guides

Kinetic Theory Of Gases

More Kinetic Theory of Gases Previous-Year Questions — Page 6

Q31 jee_main_2024_31_jan_morning Kinetic Energy Of Gas Molecules
The parameter that remains the same for molecules of all gases at a given temperature is :
  • A. kinetic energy
  • B. momentum
  • C. mass
  • D. speed

Solution

Related Formula
KE = (f)/(2)kT
Core Logic

The average translational kinetic energy of any gas molecule depends only on the absolute temperature of the gas and is independent of the nature or mass of the gas.

For 1 mole of any ideal gas, the average translational kinetic energy is (3)/(2)RT. Therefore, at a given temperature, the kinetic energy parameter is uniform across all ideal gases.

Pattern Recognition

Temperature is directly proportional to average translational kinetic energy. If T is constant, KE is constant for all gases regardless of mass.

Chapter Mix

Class 11 Physics: Kinetic Theory

More Kinetic Theory of Gases Questions — jee_main_2025_07_april_evening

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JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)