$A$ micelle formed during the cleansing action by soap is

Identify the option having the correct set of True $(T)$ or False $(F)$ statements with respect to colloidal solutions:
$(I)$ Lyophobic colloids are heavily solvated by the dispersion medium.
$(II)$ Multimolecular colloids are usually lyophilic.
$(III)$ Surface tension of a starch aqua sol will be lesser than that of water.
$(IV)$ Blood gets coagulated by the addition of $NaCl$.

The ability of an ion to bring about coagulation of a given colloid depends upon

The density of gold is $19 \, g/cm^3$. If $1.9 \times 10^{-4} \, g$ of gold is dispersed in $1 \, L$ of water to form a sol of spherical gold particles of radius $10 \, nm$,find the number of gold particles per $nm^3$ in the sol.

Fog is an example of a colloidal system of:

Give information about coagulation or precipitation.