Question

Butter is a colloidal formed when
A) fat is dispersed in fat
B) fat is dispersed in water
C) water is dispersed in fat
D) suspension of casein water

Answer 1

Hint: A colloid is a homogeneous mixture of substances (also called different phases) in which one substance (soluble or insoluble) is evenly distributed throughout the other substance. The substance which is less in amount is termed as the dispersed phase and the other which is more in amount is termed as a dispersion medium.

Complete answer:Now, in the case of butter we all have observed that the substance or the phase which can be termed as dispersed phase is water because it is less in amount, and fat makes the dispersion medium. So, butter can be called water dispersed in fat.

Our final answer is ‘C’ i.e. water dispersed in fat.

Additional Information:
The materials which are made up of two or more substances combined physically (not chemically) are called mixtures. There are three types of mixtures: true solutions, colloids, and suspensions. The true solutions and colloids are homogeneous mixtures (i.e. one substance is evenly distributed into the other) whereas suspensions are heterogeneous mixtures (i.e. one substance is not evenly distributed into the other). True solutions are mixtures in which one substance dissolves into the other. Suspensions are mixtures in which larger particles of one substance float around freely in another substance and finally settle down after some time. Colloids have already been explained above.

Note:
In order to decide the nature of the colloid, it is very important to differentiate between the dispersion medium (phase larger in amount) and the dispersed phase. Always keep in mind that the phase larger in amount is dispersion medium and lesser in amount is the dispersed phase. A colloid is then named as the dispersed phase in the dispersion medium. Here, water is fat.