Question

Which among the following is an unsaturated compound?
(A) ${C_5}{H_{14}}$
(B) $C{H_3}OH$
(C) ${C_3}{H_7}OH$
(D) ${C_4}{H_8}$

Answer 1

To solve this question, let’s first understand the difference between the saturated and unsaturated compounds. So, the saturated compounds are those compounds that contain single bonds i.e. atoms in a compound are joined by only single bonds.

Complete answer:
On the other hand unsaturated compounds can be defined as the compounds that contain double or triple bonds i.e. atoms in the compounds are joined by double or the triple bond unlike in saturated compounds.
So, examples of saturated compounds are the alkanes.
And the example of unsaturated compounds are the alkenes and the alkynes.
So, among the given different options we can see that ${C_4}{H_8}$ is an alkene. It has a formula of ${C_n}{H_{2n}}$ . So, clearly this butene will have a double bond to satisfy its valency of electrons. Hence, it is an unsaturated compound.
All the other given options are alkanes or forms of alkanes and do not contain double or triple bonds and thus are the saturated compounds.
Therefore, the correct option is D.

Note:
However, in the laboratories we can perform a test to detect unsaturation i.e. to know whether a compound is saturated or unsaturated. This is done by performing a test known as bromine test. Bromine test is a qualitative test that detects the unsaturation and gives the bromine colour or the coloured solution. The more the unsaturation is, the more the coloured the solution the solution is. Whereas, unsaturated compounds yield colourless solutions in bromine tests. So, this test is an easily detectable method to distinguish between the unsaturated and saturated compounds.