Which is the correct statement in the case of milk?

The surface tension of a hydrophilic sol is:

Which one of the following is not a colloid?

When $FeCl_3$ is added to an excess of hot water,it gives a sol '$X$'. When $FeCl_3$ is added to $NaOH_{(aq)}$ solution,it gives a sol '$Y$'. The sols '$X$' and '$Y$' formed in the above processes respectively are:

Which of the following statements is incorrect about colloidal solutions?

On adding a few drops of dilute $HCl$ or $FeCl_3$ to freshly precipitated ferric hydroxide,a red-coloured colloidal solution is obtained. This phenomenon is known as: