Arrange the elements in each of the following groups in increasing order of the most positive electron affinity.
F,Cl,Br,I

Explanation

`I lt Br lt F lt Cl.` It is known that electron affinity of third period elements is higher than their second period counter- parts. For instance, chlorine has higher electron affinity than fluorine. As fluorine is small and has high electron density it shows a tendency to repel the incoming electron.