Question

A solution is a homogeneous mixture of two or more substances. Which of the following is a solution?
A) Milk
B) Smoke
C) Brass
D) Face cream

Answer 1

Hint: A solution is a homogeneous mixture of two or more substances which consists of one phase. Homogeneity is something that is evenly distributed.

Complete step by step solution:
It is also the mixture of solute and solvent. Solute is the substance being solved. Solvent is the substance in which the solute is dissolved. If all the particles in the solution are in the same phase, then it is called homogeneous solution. For example, air is a mixture of different types of gases like oxygen, nitrogen, etc.
A. Milk is visibly a homogeneous mixture, but when observed under a microscope, it has tiny particles of fats and proteins. Thus it is not a solution. Colloidal solutions are the solutions in which one substance is suspended over another.
B. Smoke is a colloidal mixture of solid particles in liquid or gas. Thus it is called a solid aerosol in which the dispersed phase is solid and the dispersion medium is gas. Some examples are mist, dust, fog etc.
C. Brass is an alloy of copper and zinc. Metals or metals with nonmetals mixed homogeneously are called alloys. Therefore this is an example of a solution. This is a solution of two solids. Percentage composition of copper in brass is $70\% $and that of zinc is \[30\% \].
D. Face cream is an example of emulsion. Emulsion is a colloidal solution in which dispersing medium and dispersed phase are liquid.

Therefore, Option C) is the correct answer.

Additional information:
A solution need not be in the liquid phase. It can be of two solid mixtures also. But both should be in the same phase.

Note:
Smoke, face cream, milk are examples of colloidal solutions. Colloids are classified on the basis of their dispersing medium and dispersed phase. They are liquid aerosol, solid aerosol, foam, emulsion, sol, solid foam, gel, solid sol.