When a gas is taken from one state `a` to another state `b` via one path, it absorbs `25 calories` of heat while doing `70J` of work. How much heat much heat has to be supplied in taking the same gas from state `a` to state `b` via another path when it performs `200J` of work?

Answer

`235J`

Explanation

In the first case,
`dQ= 25 cals = 25xx4.2J= 105J`
`dW= 70J`
From `dQ=dU+dW`
`dU=dQ-dW= 105-70= 35J`
In the second case,
As the gas is taken between the same two states, therfore, `dU'= dU= 35J`
`dQ'=dW'= 200J`
From `dQ'=dU'+dW'= 35+200= 235J`