Which of the following is a lyophilic colloid?

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 .......

If $1000 \ mg$ of a lyophilic colloid prevents the coagulation of $100 \ mL$ of a lyophobic sol,then the gold number (protective value) is ......... $mg$.

Which of the following makes the lyophilic solution unstable?

Fog is a dispersion of

Which of the following statements is/are not true?