A compound has 8 moles of hydrogen and 4 moles of carbon.
The empirical formula of the compound is:

The empirical formula can be C₄H₈ or CH₃-CH=CH-CH₃.

Explanation:

As the number of moles of each element is already given ,then there is no need of further calculations. We can get the empirical formula by writing the moles of each element in its subscript position. As empirical formula is one of the simplest way to represent any chemical compound. So the given compound can be written as CₓHₙ. Here x and n are the number of moles of carbon and hydrogen present in the compound.

Since it is stated as the 4 moles of Carbon and 8 moles of hydrogen is present and it is known that each carbon can have maximum four single bond with its neighbors, so the empirical formula can be written as

C₄H₈ or CH₃-CH=CH-CH₃

Thus, the empirical formula can be C₄H₈ or CH₃-CH=CH-CH₃.

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.