$A$ colloidal system in which gas bubbles are dispersed in a liquid is known as

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

$A$ is a protecting colloid. The following data is obtained for preventing the coagulation of $10 \text{ mL}$ of gold sol to which $1 \text{ mL}$ of $10\% \text{ NaCl}$ is added. What is the gold number of $A$?

$1$. Expt. No.	$2$. Wt (in mg) of $A$ added to gold sol	$3$. Coagulation
$1$	$40$	Prevented
$2$	$35$	Prevented
$3$	$25$	Not prevented
$4$	$32$	Not prevented
$5$	$33$	Prevented

The gold numbers of protective colloids $A, B, C$,and $D$ are $0.04, 0.004, 10$,and $40$ respectively. The order of their protective power is:

Which of the following electrolytes is the most effective for the coagulation of ferric hydroxide sol?

When freshly prepared $Fe(OH)_3$ precipitate is boiled in water in the presence of a few drops of dilute $HCl$,a colloidal sol of ferric hydroxide is formed. This process is known as .......