Final answer:
Entropy change (ΔS) is positive for the melting of ice and boiling of water, as these processes increase disorder. Conversely, condensing steam and freezing liquid have negative entropy changes because they decrease disorder. Option A and B is correct.
Step-by-step explanation:
The question involves understanding the concept of entropy, which is related to the disorder or randomness in a system. Entropy changes (ΔS) can either be positive or negative, depending on whether the process increases or decreases the disorder of the system.
- Melting ice (ΔS positive): When ice melts, it goes from a solid to a liquid state. This increases the disorder, as the molecules in the liquid have more freedom to move around than they do in the solid state.
- Boiling water (ΔS positive): Boiling water turns it from a liquid to a gas, greatly increasing the disorder because the gas molecules are much more spread out and can move more freely than liquid molecules.
- Condensing steam (ΔS negative): Condensing steam turns it from a gas to a liquid, which reduces the disorder since the molecules in a liquid are closer together and have less freedom than in a gaseous state.
- Freezing liquid (ΔS negative): Freezing a liquid into a solid makes its molecules arrange more orderly, which decreases the disorder and therefore results in a negative change in entropy.
In conclusion, processes that involve a change from solid to liquid or liquid to gas tend to have positive entropy changes because they denote an increase in disorder. Conversely, processes that involve a change from gas to liquid or liquid to solid tend to have negative entropy changes due to a decrease in disorder.