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

The surface tension of a soap solution is $30 \times 10^{-3} \, N/m$. The work done to increase the surface area of a soap film from $5 \, cm \times 5 \, cm$ to $10 \, cm \times 10 \, cm$ is:

Which of the following is not an emulsion?

Tyndall phenomenon is exhibited by

Which of the following ions will be most effective in coagulating the $As_2S_3$ sol?

$A$ fresh precipitate can be transformed into a colloidal mixture by -