Why is gelatin mixed in ice-cream?

$A$ 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

Identify a zero dimensional nano structure from the following.

Some substances behave as electrolytes in dilute solutions and as colloids in their concentrated solutions. Their colloidal forms are said to form

$10 \ mL$ of $0.5 \ M$ $NaCl$ is required to coagulate $1 \ L$ of $Sb_2S_3$ sol in $2$ hours. The flocculating value of $NaCl$ (in millimoles) is:

Which of the following is an example of multimolecular colloids?