Which one of the following is correct for the adsorption of a gas...

Which one of the following is correct for the adsorption of a gas at a given temperature on a solid surface?

Options

A $\Delta H > 0, \Delta S > 0$
B $\Delta H 0$
C $\Delta H > 0, \Delta S < 0$
D $\Delta H < 0, \Delta S < 0$

Correct answer

D. $\Delta H < 0, \Delta S < 0$

Step-by-step solution

Adsorption is spontaneous process therefore change in free energy is negative. Adsorption of gas on solid surface is exothermic process & entropy is decrease in this process so

$\Delta H < 0, \Delta S < 0$

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