Question

The emulsifying agent used in o/w emulsion is:
A.Protein
B.Long chain alcohol
C.Lampblack
D.Heavy metal salts of fatty acids.

Answer 1

Emulsion: Those colloidal solutions in which dispersion phase and dispersion medium both are liquids, are known as emulsion. o/w emulsion means oil is dispersed phase and water is dispersion medium.

Complete step by step answer:
First of all we will talk about colloidal particles, dispersed and dispersion mediums.
Colloidal mixtures: It is defined as the mixture in which the tiny particles are suspended throughout another substance.
Dispersion phase: The phase in which the colloidal particles exist, are known as dispersed phases.
Dispersion medium: The medium in which the colloidal particles are distributed, is known as dispersion medium.

Dispersed phase	Dispersion medium	Name of the colloid	Example
Solid	Solid	Solid sol	Alloys
Solid	Liquid	Sols	Paints, jellies
Solid	Gas	Aerosol	Dust, smoke
Liquid	Solid	Solid emulsion	Butter, cheese
Liquid	Liquid	emulsion	Milk, cream
Liquid	Gas	Liquid aerosol	Mist, cloud, foam
Gas	Solid	Solid foam	Marshmallow
Gas	liquid	Foam	Whipped cream

Now emulsions are of two types: water in oil it is represented as w/o and oil in water it is represented as o/w. In w/o type emulsions the dispersed phase is water and dispersion medium is oil. For example: butter. In o/w type emulsions the dispersed phase is oil and dispersion medium is water. For example: milk.
Emulsifying agent: The substance which acts as stabiliser (which prevents separation of two non-mixing liquids) for emulsions, is known as emulsifying agent. Emulsifying agents are also known as emulsifiers. For o/w type emulsions the emulsifying agent used is proteins. For milk which is an example of oil i.e. fat in water the emulsifying agent is protein. And for the water in oil i.e. w/o type emulsions emulsifying agents are lampblack, long chains alcohols and Heavy metal salts of fatty acids.
Hence, the emulsifying agent used in o/w emulsion is protein.

So option A is correct.

Note:
Proteins are polymers of amino acids. Amino acids are made up of carboxylic acids and amine groups so they can act as acid as well as base that's why they are called amphoteric compounds. If the groups i.e. carboxylic acids and amine are equal in number then they are called as neutral amino acids.