Final answer:
In a reversible process, the change in entropy of the system is equal in magnitude but opposite in sign to the change in entropy of the surroundings.
Step-by-step explanation:
In a reversible process, the change in entropy of the system (ΔS-sys) is equal in magnitude but opposite in sign to the change in entropy of the surroundings (ΔS-surr). This can be represented by the equation: ΔS-sys = -ΔS-surr.
When heat flows from the system to the surroundings, the system loses entropy while the surroundings gain entropy. The magnitudes of the entropy changes are equal, but the signs are opposite, resulting in the equation mentioned above. This relationship holds true for reversible processes only.