Entropy

When steam condenses to water at $90°\mathrm{C}$, the entropy of the system decreases. What must be true if the second law of thermodynamics is to be satisfied?

[Hint: For a spontaneous process ${\mathrm{\Delta S}}_{\text{universe}}$ must be positive.]

In which of the following reactions is $\mathrm{\Delta S}$ positive?

In which of the following cases does entropy decrease?

For the following process, tell whether the entropy of the system increases, decreases or remains constant.

Freezing one mole of water to ice at $0°\mathrm{C}$ and then cooling it to $-10°\mathrm{C}$.

For the following process, tell whether the entropy of the system increases, decreases or remains constant.

Freezing one mole of water to ice at $-10°\mathrm{C}$.

For the following process, tell whether the entropy of the system increases, decreases or remains constant.

Freezing one mole of water to ice at $0°\mathrm{C}$.

For the following process, tell whether the entropy of the system increases, decreases or remains constant.

Melting one mole of ice to water at $0°\mathrm{C}$