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Chemistry · THERMODYNAMICS
हिन्दीA gas cylinder fitted with a frictionless piston contains an ideal gas. If the gas is compressed from \( 12.0\text{ L} \) to \( 4.0\text{ L} \) against a constant external pressure of \( 3.0\text{ atm} \), and simultaneously loses \( 1.2\text{ kJ} \) of heat to the surroundings, calculate \( \Delta U \) for the process. (Take \( 1\text{ L}\cdot\text{atm} = 101.3\text{ J} \))
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Correct answer · Option A
\( +1231.2\text{ J} \)
Explanation
\( w = -p_{\text{ex}}(V_f - V_i) = -3.0(4.0 - 12.0) = +24.0\text{ L}\cdot\text{atm} = 24.0 \times 101.3\text{ J} = +2431.2\text{ J} \). \( q = -1200\text{ J} \). Hence, \( \Delta U = q + w = -1200 + 2431.2 = +1231.2\text{ J} \).
