An ideal gas occupies an unknown volume V liters (L) at a pressure of 12 atm. The gas is expanded isothermally against a constant external pressure of 2 atm so that its final volume become 3 L. The work involved for this expansion process is ____ cal. (Round off to two decimal places) (Gas constant $R = 0.082\ \mathrm{L\,atm\,mol^{-1}\,K^{-1}} = 2\ \mathrm{cal\,mol^{-1}\,K^{-1}}$)
Answer
SELF-PRACTICE — the source book printed no answer.
Nothing is invented here, so this question has no answer on record.