The charge on $As_2S_3$ sol is due to the adsorbed

In which of the following is the Tyndall effect $NOT$ observed?

Among the following,the surfactant that will form micelles in aqueous solution at the lowest molar concentration at ambient conditions is

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:

Gold number is defined as:

Which of the following is/are not an example of $Gel$?