---------> sorption:-When both the adsorption and absorption occur simultaneously and are not distinguishable, such a PROCESS is called sorption.---------> positive and negative:-Negative and positive are opposites in other senses. Mathematically, there are positive (+) NUMBERS, and negative (-) numbers. I can have a positive (good) attitude, or a negative (bad) attitude. Just as "good" is the opposite of "bad" and of "EVIL," "negative"s meaning depends on what you contrast it with.--------> physisorption and chemisorption:-PhysisorptionPhysisorption is also known as physical adsorption and it is an exothermic process. Its adsorption ENTHALPY is low, nearly 20 to 40 kJ/mol. Normally in physisorption, the gas is accumulated on the solid surface due to weak force, known as Van der Waals forces.chemisorption Chemisorption is also known as chemical adsorption. In chemisorption, adsorption takes place in adsorbed substance that is held by chemical bonds. Chemisorption has high specificity that is it is highly specific, and it takes place only if there is a chemical bonding between adsorbent and adsorbate.adsorption isotherm Adsorption Isotherm is a curve that expresses the variation in the amount of gas adsorbed by the adsorbent with pressure at constant temperature.