JEE Main · 2026 · 21 Jan 2026 · Shift 1 · Chemical Thermodynamics

The work done by a gas equals the area under its pressure-volume curve during expansion. An isochoric change encloses no area and gives zero work, while a closed cyclic path returns the gas to a smaller volume, so its net work is only the area trapped inside the loop. The single expansion that runs from the high-pressure state down to the low-pressure state sweeps the entire area beneath the curve between the initial and final volumes, the largest of the four cases. That smooth expansion curve represents the maximum work done.