Question

Which one of the following hydrocarbons can show isomerism?
A. ${C_2}{H_4}$
B. ${C_2}{H_6}$
C. ${C_3}{H_8}$
D. ${C_4}{H_{10}}$

Answer 1

Hint: For showing the presence of isomerism in a structure the structure should have the minimum two possible structures which are isomers of each other. One can draw the possible number of isomeric structures for each option analyzing one by one and can find out the answer.

Complete step by step answer:
-First of all let us understand the concept of isomerism, the isomerism is the term in which more than one compounds have the same chemical formula i.e. molecular formula but have different chemical structures i.e. different structural formula.
-The chemical compounds or structures that have identical chemical formulas but they differ in the chemical properties and the arrangement of atoms present in the molecule are called isomers.
-Now as we have understood the concept of isomerism and after analyzing the chemical formulas given in the above options we came to the conclusion that the ${C_2}{H_4}$, ${C_2}{H_6}$, ${C_3}{H_8}$ can not give any isomers and hence, does not show isomerism.
-In the chemical formula ${C_4}{H_{10}}$, it shows the isomers as shown below,
$C{H_3} - C{H_2} - C{H_2} - C{H_3}$ AND $C{H_3} - CH(C{H_2}) - C{H_3}$
Therefore, the chemical compound butane gives structural isomers as $n - $butane as the first isomer and $2 - $methyl butane as the second isomer.
Therefore option D is a correct choice of answer.

Note: The above two isomers of butane show the chain isomerism which is the type of structural isomerism. The chain isomers can also be called skeletal isomers as they differ in the carbon skeletal structure of the molecule. The two isomers of the same molecule do not show the same chemical and physical properties.