Two equal masses of water at 60 °C and 40 °C are mixed adiabatically in a perfectly insulated beaker. Which one of the following statements correctly describes the entropy change (ΔS)?
a) ΔSsys<0,ΔSsurr>0
b) ΔSsys=ΔSsurr=0
c) ΔSsys>0,ΔSsurr=0
d) ΔSsys>0,ΔSsurr<0