Identify that oxide of nitrogen without reference to

Question

Please explain in detail. Thank you!

1.Predict the sign of ΔS for each process:

1. the boiling of water
2. I₂(g) → I₂(s)
3. CaCO₃(s) → CaO(s) + CO₂(g)

2. All the oxides of nitrogen have positive values of ΔG°_f at 298 K, but only one common oxide of nitrogen has a positive ΔS°_f. Identify that oxide of nitrogen without reference to thermodynamic data and explain.