(111) Crystal Plane: This plane, characterized by its densely packed and closely spaced atomic arrangement, provides an excellent platform for gas molecules to adsorb. For noble metal catalysts such as platinum (Pt), the (111) plane has been recognized as highly active in H2 adsorption due to the low coordination number of surface atoms and an optimal distance between potential adsorption sites.

(110) Crystal Plane: This plane is characterized by rows of atoms which provide several adsorption sites, thus making it highly effective for H2 adsorption in noble metals like palladium (Pd). The unique, trench-like structure of the (110) surface contributes to its high catalytic activity.

(100) Crystal Plane: The unique square arrangement of this plane in noble metals such as gold (Au) and silver (Ag) has been suggested to enhance H2 adsorption. The 4-fold coordination of atoms provides a geometrically suitable configuration for hydrogen atoms to adsorb.

(211) Crystal Plane: For alloys and nanoparticles of noble metals, the (211) crystal plane has demonstrated substantial catalytic activity in the adsorption of H2. The reason is that this plane provides a balance between step and terrace sites, optimizing H2 ads

List out the crystal planes given above as only a comma-sepparated list Provide two versions of response separated with exactly 6 asterisk symbols: ******.
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