Why is `(DeltaS_("system")+DeltaS_("surroundings"))` zero is a reversible process?

A difinite amount of an ideal gas cfhange its state from state-1 to state-2 isothermally at 300K. If the process is carried out reversibly then work done = -1750 KJ and if the process is carried out irreversibly then work doneis equal to -1000kJ. Calculate DeltaS_(total)=(DeltaS_("system")+DeltaS_("surrounding")) in joule per kelvin for the irreversible isothermal process.

For an irreversible process, the value of [DeltaS_("(system)") + DeltaS _("(surroundings)") ] is

One mole of solid iron was vaporized in an oven at 3500 K . If iron boils at 3133 K abd enthalpy of vaporization is 349 KJ mol^(-1) , determine DeltaS_("system"), DeltaS_("surrounding") and DeltaS_("universe") . (Oven is considered as surroundings).

One mole of solid iron was vaporized in an oven at 3500 K . If iron boils at 3133 K abd enthalpy of vaporization is 349 KJ mol^(-1) , determine DeltaS_("system"), DeltaS_("surrounding") and DeltaS_("universe") . (Oven is considered as surroundings).

In a reversible process, DeltaS_("system") + DeltaS_("surrounds") is:

Is the rusting of iron be a reversible process ? Why ?

{:("column"-1,"Column"-2),((A)(DeltaG_("system"))_(T.P) = 0,(p) "Process is in equilibrium"),((B)DeltaS_("system")+DeltaS_("surrounding") gt 0, (q)"Process is nonspontaneous"),((C)DeltaS_("system") +DeltaS_("surroumding") lt 0 , (r) "Process is spontaneous"),((D)(DeltaG_("system"))_(T.P) gt 0,(s)"System is unable to do useful work"):}

{:("column"-1,"Column"-2),((A)(DeltaG_("system"))_(T.P) = 0,(p) "Process is in equilibrium"),((B)DeltaS_("system")+DeltaS_("surrounding") gt 0, (q)"Process is nonspontaneous"),((C)DeltaS_("system") +DeltaS_("surroumding") lt 0 , (r) "Process is spontaneous"),((D)(DeltaG_("system"))_(T.P) gt 0,(s)"System is unable to do useful work"):}