Final answer:
For a spontaneous process, when the entropy change of the system (ΔSsys) is negative, the entropy change of the surroundings (ΔSsurr) must be positive to ensure that the total entropy change of the universe is positive.
Step-by-step explanation:
When ΔSsys is negative, ΔSsurr must be positive for a spontaneous process. This is because spontaneity is determined by the overall change in entropy of the universe (ΔSuniv), which must be positive for a process to occur spontaneously. According to the second law of thermodynamics. If the system (ΔSsys) loses entropy, the surroundings (ΔSsurr) must gain enough entropy to result in a positive total entropy change of the universe.