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NEET
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Physics
Chapter
Thermodynamics

NEET · Physics · Thermodynamics

An ideal gas expands from an initial volume V to a final volume 2V...

An ideal gas expands from an initial volume VV to a final volume 2V2V through three different processes starting from the exact same initial state. The processes are isobaric, isothermal, and adiabatic. Let W1W_{1}, W2W_{2}, and W3W_{3} be the magnitudes of the work done by the gas in the isobaric, isothermal, and adiabatic processes respectively. Which of the following correctly represents the relationship between the work done in these processes?

Options

  1. AW3>W2>W1W_{3} > W_{2} > W_{1}
  2. BW1>W2>W3W_{1} > W_{2} > W_{3}
  3. CW2>W3>W1W_{2} > W_{3} > W_{1}
  4. DW1=W2=W3W_{1} = W_{2} = W_{3}

Correct answer

B. W1>W2>W3W_{1} > W_{2} > W_{3}

Step-by-step solution

The magnitude of work done by a gas during expansion is equal to the area under the P-V curve for that process.

Starting from the same initial state (P,V)(P, V) and expanding to the same final volume 2V2V:

In an isobaric process, the pressure remains constant, so its P-V curve is a horizontal line.

In an isothermal process, the pressure decreases as volume increases. Its curve falls below the isobaric line.

In an adiabatic process, the pressure decreases more rapidly than in an isothermal process because its curve is steeper (slope is γ\gamma times the isothermal slope). Its curve falls below the isothermal curve.

Therefore, the area under the curves follows the order: Area(isobaric) > Area(isothermal) > Area(adiabatic).

This means the work done follows the sequence: W1>W2>W3W_{1} > W_{2} > W_{3}.

Answer: W1>W2>W3W_{1} > W_{2} > W_{3}
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