Emulsifiers are generally

When the dispersion medium in a colloidal system is a gas,it is called ....

The stabilisation of a lyophobic colloid is due to

Explain the cleansing action of soaps.

Which of the following is not a property of a sol?

When a few drops of dilute $HCl$ are added to a freshly prepared precipitate of ferric hydroxide,a reddish-brown colloidal solution is obtained. This phenomenon is known as .......