Final answer:
In the processes listed, sublimation and combustion result in an increase in entropy (positive ΔS), while freezing and condensation lead to a decrease in entropy (negative ΔS).
Step-by-step explanation:
The student asked which of the following processes has a change in entropy (ΔS): sublimation, freezing, combustion, or condensation. Entropy (ΔS) is a measure of the molecular disorder or randomness in a system. In phase changes, ΔS can be positive or negative, depending on whether the matter is becoming more disordered (positive ΔS) or more ordered (negative ΔS).
Sublimation is the conversion of a solid directly to a gas, resulting in a much greater dispersal of matter. This process involves an increase in entropy (positive ΔS). Freezing is the conversion of a liquid to a solid, resulting in a decrease in entropy (negative ΔS) as the molecules become more ordered. Combustion is a chemical reaction that typically increases the number of moles of gaseous products, which would mean an increase in entropy (positive ΔS). Lastly, condensation is the conversion of a gas to a liquid, which decreases the entropy (negative ΔS) because the molecules become more ordered.
Thus, sublimation and combustion are processes where entropy increases, while freezing and condensation are processes where entropy decreases.