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An ideal gas expands in volume from 1 × 10⁻³ to 1 × 10⁻² m³ at 300 K against a constant pressure of 1 × 10⁵ N m⁻². The work done is

1. 270 kJ
2. −900 kJ
3. −900 J
4. 900 J

Correct answer: −900 J

Solution

Work done on the gas during expansion against constant external pressure = -P_ext*Delta_V = -(1e5)(1e-2 - 1e-3) = -900 J.

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