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Kinetic Theory of Gases appeared 26 times across 3 years — 3% of Physics. This question is from Gas Laws and Temperature Dependency.

Year 2026 2025 2024 Total
Questions 6 11 9 26
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Pressure of an ideal gas, contained in a closed vessel, is increased by 0.4% when heated by 1°C. Its initial temperature must be :

Solution & Explanation

Related Formula

For an ideal gas in a closed container, the volume V remains constant (isochoric process). By Gay-Lussac's Law:

P ∝ T ⇒ (Δ P)/(P) = (Δ T)/(T)

where T must be in Kelvin.

Core Logic

Given parameters:

  • Percent increase in pressure: (Δ P)/(P) × 100 = 0.4% ⇒ (Δ P)/(P) = 0.004
  • Increase in temperature Δ T = 1°C = 1~K
Step 1: Calculate initial temperature (T)

Substitute the values into Gay-Lussac's fractional variance formula:

0.004 = (1)/(T) T = (1)/(0.004) = 250~K
Pattern Recognition

A standard percentage-increase layout. A change of 0.4% means (1)/(250) of the original quantity. Hence, a 1~K rise corresponds to an initial temperature of 250~K directly.

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

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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%)