The enthalpy change for the adsorption process and micelle formation respectively are:

🧠 Adsorption is exothermic; micelle formation is endothermic but entropy-driven Two processes, two opposite signs:

Adsorption: gas/solute molecules lose kinetic freedom and bond to a surface → energy is released → $\Delta H_{\text{ads}} < 0$ (exothermic). ✓

Micelle formation: surfactant tails cluster together to escape the aqueous environment. The hydrophobic effect is primarily entropy-driven — the process actually has a slightly positive $\Delta H_{\text{mic}} > 0$ (endothermic). The large gain in entropy of the surrounding water molecules drives spontaneity. ✓

This matches option (c): $\Delta H_{\text{ads}} < 0$ and $\Delta H_{\text{mic}} > 0$.

⚠️ Trap: Students expect both to be exothermic because both are "thermodynamically favourable." Micelle formation is spontaneous, but its enthalpy is positive — it's entropy that drives it.

$\boxed{\text{Answer: (c)}}$