During an isothermal expansion, a confined ideal gas does –275 J of work against its surrounding. This implies that :

No heat is transferred because the process is isothermal 275 J of heat has been removed from the gas 275 J of heat has been added to the gas  550 J of heat has been added to the gas

275 J of heat has been added to the gas

By first law of thermodynamics, ΔU = Q + W For isothermal process, ΔU = 0 Thus, Q = – W ; W = – 275 Q = + 275 Thus, 275 J of heat is added to the gas.