Gold sol is not a

The protecting power of lyophilic colloidal sol is expressed in terms of

The correct statements with respect to dialysis of colloidal solution are
$I$. Colloidal particles can pass through the membrane.
$II$. Animal bladder can be used as membrane.
$III$. Cellophane is not used as membrane.
$IV$. Ions or small molecules can diffuse through membrane into water.

Measuring Zeta potential is useful in determining which property of colloidal solution?

Given below are two statements:
Statement $I :$ Emulsions of oil in water are unstable and sometimes they separate into two layers on standing.
Statement $II :$ For stabilisation of an emulsion,excess of electrolyte is added.
In the light of the above statements,choose the most appropriate answer from the options given below:

Identify the negatively charged sol from the following.