A system goes from P to Q by two different paths in the `p-V` diagram as shown in figure. Heat given to the system in path 1 is 1000 J. The work done by the system along path 1 is more than path 2 by 100 J. What is the heat exchanged by the system in path 2 ?

Explanation

For path 1, Heat given `Q_(1)` = + 1000J ltBrgt Work done = `W_(1)` (let)
For path 2,
`" "` Work done `(W_(2))=(W_(1)-100)J`
Heat given `Q_(2)`= ?
As change in internal energy between two states for different path is same.
`therefore " "DeltaU=Q_(1)-W_(1)=Q_(2)-W_(2)`
`" "1000-W_(1)=Q_(2)-(W_(1)-100)`
`rArr" "Q_(2)=1000-100=900J`