Which one of the following arrangements represents the correct order of electron gain enthalpy of the given atomic species?

Options

A. `S lt O lt Cl lt F`
B. `Cl lt F lt O lt S`
C. `O lt S lt F lt Cl`
D. `F lt S lt O lt Cl`

Answer

3

Explanation

Group `16` and `17` elements all have negative electron gain enthalpies. As we move from Group `16` to Group `17`, it becomes more negative. In Group `16`, it becomes more and more negative as we move down from S, however, O has the least negative `Delta_(eq)H` in the group on account of electron repulsion due to its small size.
In Group 17, `Delta_(eg.)H` becomes more and more negative as we move down from `Cl`, however F has less negative `Delta_(eg.)H` due to electron-electron replusion on account of its small size. Thus, the correct order of `Delta_(eg.)H` becoming more and more negative is
`O lt S lt F lt Cl`
This question can also be credited to Periodic Table (Part 1).