Asked in MDCAT Test Series 5 — Waves and Thermodynamics (7 March 2025) 2025Moderate

In a process the density of gas remains constant. If the temperature is doubled, then the change in the pressure will be:

Correct answer: A. 100% increase

  • A. 100% increase
  • B. 200% increase
  • C. 50% decrease
  • D. 25% decrease

Explanation

In an ideal gas where the density remains constant, the relationship between pressure (P), volume (V), and temperature (T) is given by the ideal gas law: PV = nRT. Since density (ρ) is constant, we can express it as ρ = PM/RT. If the temperature (T) is doubled and density remains constant, the pressure must also double to maintain the equation. Therefore, if the initial pressure is P1, the new pressure P2 will be 2P1, indicating a 100% increase in pressure. The other options are incorrect because they do not reflect the proper relationship between pressure and temperature under these conditions.

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About Thermal Equilibrium and Heat

Thermal equilibrium means that bodies in contact have the same temperature and no net heat flows between them. The topic distinguishes heat from temperature, uses the zeroth law of thermodynamics, and covers heat transfer, specific heat capacity, thermal expansion and the conditions for reaching equilibrium.

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