• A colloid is a mixture in which one of the substances is split into very minute particles which are dispersed throughout a second substance. The substance which is dispersed is called a dispersed phase whereas the one in which the first substance is distributed is called a dispersion medium.
  
• The size of colloid particles generally ranges between 1 to 1000 nanometres i.e. $10^{-5}$ to $10^{-7}cm$.
  10−5 - 10−7 cm