Answer the following question from the passage below:

The process of accumulation of molecular species at the surface of solid or liquid is called adsorption. It may be physisorption or chemisorption. Low temperature is favorable for physisorption. Amount of gas adsorbed by a solid depends upon nature of gas. Easily liquifiable gases are readily adsorbed. Catalyst increases the rate of reaction. Catalysis may be homogenous or heterogenous Enzymes are biological catalysts. They work at optimum pH and temperature. Solutions are of three types i.e. true solutions, colloids and suspensions. Depending on the interaction between dispersed phase and dispersion medium colloids may be Lyophilic and Lyophobic. Depending on type of particles there may multimolecular, macro-molecular and associated colloids. Sol. gel, emulsions are also various types of colloids.

Physical adsorption may become chemisorption as:

Temperature is increased

The correct answer is option 2. Temperature is increased.

When the temperature of a system is raised, the kinetic energy of molecules within the system also increases. This heightened kinetic energy translates to greater molecular motion and collision frequency. In the context of adsorption, an increase in temperature affects the interaction between the adsorbate (the substance being adsorbed) and the adsorbent (the surface on which adsorption occurs). For physical adsorption, the bonds formed between the adsorbate and the adsorbent are relatively weak, typically van der Waals forces. As the temperature rises, molecules in the system gain more energy, increasing the likelihood of overcoming the activation energy barrier required for chemical bond formation between the adsorbate and the adsorbent. In some cases, the increased energy provided by elevated temperatures allows adsorbate molecules to interact more strongly with the adsorbent surface. This can lead to the breaking of existing weak bonds (such as van der Waals forces) and the formation of stronger chemical bonds between the adsorbate and the adsorbent. The transition from physical adsorption to chemisorption due to temperature increase is observed when the energy provided by elevated temperatures is sufficient to facilitate the formation of stronger chemical bonds between the adsorbate and the adsorbent. In summary, increasing the temperature can promote the transition from physical adsorption to chemisorption by providing the necessary energy for stronger chemical bond formation between the adsorbate and the adsorbent, thereby enhancing the adsorption process.