Question

Phenol-water system is a/an___.
A. Element
B. Compound
C. Homogeneous system
D. Heterogeneous system

Answer 1

We know that a matter or system can be categorized into different categories on the basis of its composition. We know that mixtures are of two types, homogeneous mixture and heterogeneous mixture. A mixture which possesses a uniform composition all over the solution is called homogeneous mixture, whereas a mixture which possesses a non-uniform composition is called a non-homogeneous mixture. Milk comes under the category of non-homogeneous mixture.

Complete answer
Scientists have always made efforts to systemize the knowledge that have been gathered so as to make a better understanding of it that can be used effectively without any chaos. The matter around all of us has different properties and it was found that the reason for this is the difference in the composition of matter. On a very basic level, we can now classify the matter depending upon its composition.
Matter can either be made from pure substances or mixture of pure substances. We can further divide pure substances as elements and compounds.
1. Elements: These are made of only one type of atoms and no physical or chemical method can break them down any more. The examples include carbon and chlorine.
2. Compounds: These are made by combination of two of more elements in a fixed ratio and can be broken down into constituting elements by employing chemical methods. Examples include water and ammonia.
Now, we have mixtures which are prepared by mixing multiple pure substances in a random ratio. We can classify these as homogeneous and heterogeneous mixtures depending on the uniformity of composition.
1. Homogeneous mixtures: These mixtures have uniform composition throughout. The examples include air and aqueous solution of salt.
2. Heterogeneous mixtures: These mixtures do not have uniform composition throughout. Suspensions and colloids are heterogeneous systems. The examples include milk and solution of starch.
Now, let’s try to classify the given phenol-water system by using the above discussion. We know that these two are different compounds and phenol is only partially soluble in water. So, the composition would not be uniform throughout the mixture making phenol-water, a heterogeneous system.

**Hence, the correct option is D.

Note:**
We have to first check the solubility of the components then only the nature of the system can be deduced. We know that, when the components of the homogeneous mixture are all in the same phase, it is known as the solution.