The size of a colloidal particle is

Who introduced the concept of $Gold \ Number$?

Liquid-liquid sols are known as

The qualitative sketches $I$,$II$,and $III$ given below show the variation of surface tension with molar concentration of three different aqueous solutions of $KCl$,$CH_3OH$,and $CH_3(CH_2)_{11}OSO_3^{-}Na^{+}$ at room temperature. The correct assignment of the sketches is

Milk is a colloid in which

The gold numbers of gelatin,haemoglobin,and sodium acetate are $0.005$,$0.05$,and $0.7$ respectively. Their protective power will be in the order: