(i) Animal hides are colloidal in nature.
It is positively charged particles
When it is soaked in tanning, which is negatively charged colloidal particles, mutual coagulation takes place.
Which results in the hardening of leather.
(ii) Lyophilic colloids have great affinity for the dispersion medium as they are liquid loving Hence lyophilic sol is more stable than lyophobic sols.
(iii) It is necessary to remove CO when ammonia is prepared by Haber’s process because it acts as a poison and reduces the activity of catalyst ions.
Final Answer:(i) Leather gets hardened after tanning due to mutual coagulation.
(ii) Due to interaction between dispersed phase and dispersion medium or solvated layer.
(iii) Because CO acts as a poison for a catalyst.
