Luminosity observed as a result of scattering of light by particles is observed in

How many types of emulsions are there? Which are they?

Fog is an example of ...

The stabilisation of a lyophobic colloid is due to

The coagulation value is expressed in the units 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