Question

Why are lyophobic colloids unstable than lyophilic?

Answer 1

Lyophillic sols are  stablized by electrostatic charge and hydration whereas lyophobic sols are only stablized  by charge, so they easily gets coagulated and requires a stablising agent. Hence lyophillic sols are more stable than lyophobic sols

Answer 2

The stability of lyophilic sols is a result of two factors, the presence of a charge and the solvation of colloidal particles. On the other hand, the stability of lyophobic sols is only because of the presence of a charge. Thus, the lyophilic sol is more stable than lyophobic sol due to the extensive solvation.