In the `P-V` diagram shown in figure `ABC` is a semicircle. The work done in the process `ABC` is

Explanation

`W_(AB)` is negative (volume is decreasing) and `W_(BC)` is positive (volume is increasing) and since
`|W_(BC)|gt|W_(AB)|`
`therefore` Net work doen is positive
`because` Workdone area between semicircle ltbrjgt `=pi` (pressure radius) (volume radius)
`=pi(1 atm) ((1)/(2) "litre")=(pi)/(2)atm` (litre)