Final answer:
The entropy change of the surroundings is positive for all exothermic reactions where the enthalpy change of the system is negative.
Step-by-step explanation:
The entropy change of the surroundings is positive for all exothermic reactions (enthalpy change of the system is negative). During an exothermic process like the combustion of a fuel, energy is released and some of that energy is used to increase the entropy of the surroundings. This is reflected in the equation AS surr = -AH sys / T, showing that the entropy change of the surroundings (AS surr) is directly proportional to the negative enthalpy change of the system (AH sys). Since the enthalpy change is negative in exothermic reactions, the entropy change of the surroundings is positive.