Many lyophilic sols and few lyophobic sols when coagulated under some special conditions changes into semi rigid mass, enclosing whole amount of liquid within of liquid within itself, it is called gel and the process is called gelation. Gelatin, agar-agar, gum-Arabic can be converted into gels by cooling them under moderate concentration conditions. Hydrophobic sols like silicic acid. `Al(OH)_(3)` are prepared by double decomposition and exchanged of solvent method. Types of gel : 1. Syneresis/weeping of gel : The spontaneous liberation of liquid from a gel is called syneresis or weeping of gels. It is reverse of swelling. e.g., geletin, agar-agar show syneresis at low concentration while silicic shows it at high concentration. 2. Imbibition or swelling of gel : When gel is kept in a suitable liquid (water) it absorb large volume of liquid. The phenomenon is called imbibition or sweeling of gel. 3. Thixotropic : Some gels when shaken to form a sol, on keeping changes into gel are termed as thixotropic gel and phenomenon is called thixotropy. e.g., gelatin and silica liquify on shaking changing into corresponding sol and the sol on keeping changes back into gel. Which of the following is used to adsorb water?A. silica gelB. Calcium acetateC. Hair gelD. Chesse