Adsorption is the adhesion of gas molecules to a solid surface. It is always exothermic ($\Delta H<0$) because the gas loses freedom, decreasing entropy ($\Delta S<0$), and for spontaneity ($\Delta G<0$), $\Delta H$ must be negative. Physisorption (weak van der Waals forces) decreases with temperature (exothermic), while chemisorption (strong chemical bonds) first increases (needs activation energy) then decreases. Chemisorption is more exothermic and slower due to a high activation energy barrier. At high temperatures, physisorbed molecules can gain energy to overcome this barrier and form a chemisorbed layer.

Final Answer: All the given statements are correct.