Question

what is the colloidal dispersion of a liquid in a liquid called?
(A) Mixture
(B) Emulsion
(C) Precipitate
(D) None of these

Answer 1

Hint: As we know that when a colloidal immiscible liquid is mixed with another liquid then a white or cloudy substance is formed which itself is a liquid and not a solid. One liquid is dispersed into another liquid which is immiscible with it.

Complete answer:As we all know that a type of mixture of two non- mixing liquids is called emulsion. Or we can say that an emulsion is a mixture of two or more immiscible liquids in which one of the liquid contains a dispersion of the other liquid.
Common examples of emulsions include the oil and water mixture when shaken together are called emulsions where oil forms drops and disperse throughout the water. Another example includes butter which is an emulsion of water in fat.
Emulsions are generally cloudy or white in appearance. Oil in water types of emulsion are commonly used in food products like crema, a type of foam in espresso coffee, homogenised milk contains an emulsion of milk fat in water and mayonnaise also contains this type of emulsion.
The other type includes the water in oil emulsions which are rarely found in food products but still exist like the butter which involves the emulsion of water in fat and the other one is margarine.
Precipitate is the formation of a solid substance when a change in solution due to a chemical reaction or any change in temperature occurs. Hence, it is not a correct option.
Mixture is basically a result of mixing of two different substances or elements or compounds together but a chemical reaction does not necessarily take place and these substances can be of different composition and properties. Hence it is also incorrect.

Therefore the correct answer is (B).

Note:Remember that emulsions are frequently used in pharmaceutical companies, hairstyling and cosmetics like creams, ointments, pastes etc generally in the form of oil and water emulsions but in dispersed phase. Emulsifying agents are used in fire extinguishers.