In most sites I find online, I see that the Gibbs free energy of adsorption is negative. But, it is also said that physisorption is a reversible adsorption, suggesting that $\delta G=0$ which contradicts the original premise.

Hence, what exactly is the correct free energy change associated with physisorption?

From comments I learn that the reversibility is not used in the conventional thermodynamics sense but rather in the chemical reaction sense (refer). But, I don't see how it applies here since physisorption doesn't involve any bond formation.

NCERT chapter claiming the $\delta G = 0$ and reversibility condition

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    Commented Aug 21, 2021 at 14:46


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