Explain why fluorobenzene is more reactive than chlorobenzene toward electrophilic aromatic substitution but chloromethylbenzene is more reactive than fluoromethylbenzene.

Explanation:

The order of positive mesomeric effect (+M) is as follows

F>Cl>Br>I.

This implies that electron density in the respective Halobenzene is of the order

Fluorobenzene > Chlorobenzene > Iodobenzene.

This means that electrophilic aromatic substitution will also follow the same order, more the electron density more will be chances of electrophilic aromatic substitution. This means  fluorobenzene is more reactive than chlorobenzene toward electrophilic aromatic substitution

However, methyl group is attached in ring, beacuse of starric hindrance, chloromethylbenzene is more reactive than fluoromethylbenzene.

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.

the answer is 1 i believe