From an equilibrium state A to another equilibrium state A to another equilibrium state B an amount of work equal to 30 J is done on the system .if the gas is taken from state A to B iva a process in which the net heat observe by system is 10 cal , how much is the net work done by the system in the later case.
[ Take 1 cal = 4.2 J]

Explanation

Since the system is going from A to B and that back to A , it is undergoing a cyclie change Now in cyclic change there is no change in internal energy `(Delta U = 0)` .from first law of theirmodynamic
`Delta Q = Delta U + Delta W`
`= Delta W`
The amount of heat absorbed by the system `=10 cal - 30 J`
`= (10 xx 4.2 - 30 J)`
`= (42 - 30) J`
`:. ` The net work done by the system =12 J