Answer: Option (1) is the correct answer.
Explanation:
When two different molecules represent same molecular formula but different arrangement of atoms then they are known as isomers.
Whereas physical properties are the properties which determines the state of object or substance. That is, property which can be observed.
For example, wood is brown in color.
On the other hand, when arrangement of atoms are represented by the formula of a molecule then it is known as structural formula.
Thus, we can conclude that all isomers of octane have the same molecular formula.
