Whenever a mixture of gases is allowed to come in contact with a particular adsorbent under the same conditions, the more strong adsorbate is adsorbed to greater extent irrespective of its amount present, e.g., `H_(2)O` is adsorbed to more extent on silica gel than `N_(2)` and `O_(2)`. This shows that some adsorbates are preferentially adsorbed. It is also observed that preferentially adsorbable adsorbent can displace a weakly adsorbed substance from the surface of an adsorbent. Preferential adsorption depends on strength of attraction, surface area, polar nature and other factors.
A. HCl
B. `N_(2)`
C. `CH_(4)`
D. `H_(2)`
