Which of the following molecules is most suitable to disperse benzene in water?

$10 \ mL$ of $0.5 \ M$ $NaCl$ is required to coagulate $1 \ L$ of $Sb_2S_3$ sol in $2$ hours. The flocculating value of $NaCl$ (in millimoles) is:

The precipitation power of an electrolyte increases with:

Colloidal solution of gold is prepared by .............

Given below are two statements:
Statement $I:$ In the coagulation of a negative sol,the flocculating power of the three given ions is in the order - $Al^{3+} > Ba^{2+} > Na^{+}$
Statement $II:$ In the coagulation of a positive sol,the flocculating power of the three given salts is in the order - $NaCl > Na_{2}SO_{4} > Na_{3}PO_{4}$
In the light of the above statements,choose the most appropriate answer from the options given below:

What is the potential difference between the fixed layer and the diffused layer of opposite charges called?