Which among the following is an example of a $2$-dimensional nanostructure?

Which of the following does not show Tyndall effect?

$As_2S_3$ sol has a negative charge. The maximum coagulation power will be of:

The density of gold is $19 \ g/cm^3$. If $1.9 \times 10^{-4} \ g$ of gold is dispersed in one litre of water to give a sol having spherical gold particles of radius $10 \ nm$,then the number of gold particles per $mm^3$ of the sol will be

Which of the following is a $Gel$?

How many of the following statements are correct $:$
$(i)$ When freshly prepared precipitate are converted into colloidal solution then process is called peptization.
$(ii)$ Lyophilic sol are mostly of inorganic nature.
$(iii)$ Lyophilic sol are highly solvated as particles have great affinity for solvent.
$(iv)$ Lyophobic sols are reversible sols so special methods are required to prepare them.