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

Options

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

Answer

B

Explanation

Key Idea Electron gain enthalpy, generally, increases in a period from left to right and decreases in a group on moving downwards. However, members of III period have somewhat higher electron gain enthalpy as compared to the corresponding members of second period, because of their small size.
0 and S belong to VI A (16) group and Cl and F belong to VII A (17) group. Thus, the electron gam enthalpy of Cl and F is higher as compared to 0 and S.
`Cl and F gt 0 and S `
Between Cl and F, Cl has higher electrons gain enthaply then the F, since the incoming electron experience a greater force of repulsion because of small size of F-atom. Similar is true in case of O and S, i.e. the electron gain enthalpy of is higher as compared to O due to its small size. Thus, the correct order of electron gain enthalpy of given elements is
`O lt S lt F lt Cl`