During an isothermal expansion, a confined ideal gas does - 140 J of work against its surroundings. This implies that:
140 J of heat has been added to the gas
140 J of heat has been removed from the gas
280 J of heat has been added to the gas
No heat is transferred because the process is isothermal
Using
First law in Isothermal Process -
- wherein
Isothermal process
Heat supplied is equal to work done.
For an isothermal process,
as ideal gas does of work against its surroundings
Hence, heat is given to the system.