Question

Which one of the following arrangements represents the correct order of electron gain enthalpy of the given atomic species?
A. `Cl lt F lt S lt O`
B. `O lt S lt F lt Cl`
C. `S lt O lt Cl lt F`
D. `F lt Cl lt O lt S`

Answer 1

Correct Answer - B
Halogens have very high electron affinity. It may be rated that the electron affinity of fluorine is unexpectedly low `(lt Cl)`. This may perhaps be due to small size of F atom. The value of electron gain enthalpies for Cl, F, S and O are respectively 349, 333, 200 and 142 kJ/mol, hence correct order is `ClgtFgtSgtO`.