JEE Advanced levelSingle correct optionDifficulty 3 of 3td069
Five moles of an ideal gas absorb 6.00kJ of heat at constant pressure, and the temperature rises by 20.0K. Taking R=8.314Jmol−1K−1, the change in internal energy of the gas is
A6.83kJ
B6.00kJ
C5.17kJ
D0.83kJ
Answer: C
At constant P, qp=nCpΔT gives Cp=6000/(5×20)=60.0Jmol−1K−1, so Cv=Cp−R=51.69. Then ΔU=nCvΔT=5×51.69×20=5.17kJ (equivalently qp−nRΔT=6000−831.4J).