Chemistry - Surface Chemistry Question with Solution | TestHub

Explanation:

A. Spontaneous adsorption is exothermic ($\Delta H<0$) and leads to decreased entropy ($\Delta S<0$). For spontaneity, $\Delta G=\Delta H-T\Delta S$ must be negative. A negative $\Delta H$ and negative $\Delta S$ can make $\Delta G$ negative, especially at lower temperatures.

B. Micelle formation occurs ABOVE the Kraft temperature ($T_K$) and ABOVE the critical micelle concentration (CMC).

C. Adding excess NaOH to FeCl₃ forms a negatively charged Fe(OH)₃ sol (due to adsorption of OH⁻ ions), which moves towards the anode during electrophoresis.

D. According to Hardy-Schulze rules, coagulation power is proportional to the charge on the coagulating ion. Thus, Fe³⁺ > Ba²⁺ > Na⁺. Coagulation value is inversely proportional to coagulation power. Therefore, the coagulation value of Fe³⁺ will be LESS than Ba²⁺ and Na⁺.