Chemistry Answer the following questions:

Chemical adsoiption or chemisorption.

Physical adsorption or physisorption.

True.

True.

False.The rate of adsorption of gases on charcoal powder increases on lowering of temperature at a given pressure.

Generally, greater the valency of the flocculating ion added, greater is its power to cause precipitation. This is known as Hardy-Schulze rule.

The precipitation of colloids by removal of charge associated with colloidal particles is called coagulation.

• When lyophilic sol is evaporated, the dispersed phase separates.
• However, if the dispersed phase is remixed with the medium, the sol can be formed again.

Hence, lyophilic sols are called reversible sols.

Colloids can be classified in three different ways:

• Physical states of dispersed phase and dispersion medium
• Interaction or affinity of phases
• Molecular size

A catalyst is a substance which when added to a reacting system, increases the rate of a reaction without itself undergoing any permanent chemical change.

Adsorption of hydrogen on glass is an endothermic process because heat is absorbed during the process due to dissociation of hydrogen.

Chemisorption involves a large energy of activation and hence, it is also referred as activated adsorption.

The process of removal of an adsorbed substance from a surface on which it was adsorbed is called desorption.

i. Adsorbent: The material or substance present in the bulk, on the surface of which adsorption takes place is called adsorbent.
ii. Adsorbate: The substance getting adsorbed on the adsorbent is called as adsorbate.

A measure of the elastic force at the surface of a liquid is called surface tension. ### Surface tension is the amount of energy required to stretch or increase the surface of a liquid by a unit area.

(i – c),(ii – d),(iii – b),(iv – a)

(i – c),(ii – a),(iii – b)