Which one of the sols acts as a protective colloid?

Which of the following impurities can be separated from a colloidal solution by electrodialysis?

Which one of the following statements is not correct?

An emulsion is a colloidal solution containing ........

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

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.