Import Question JSON

$\text{HINT : Electron gain enthalpy, generally, increases in a period from left to right and decreases in a group on moving downwards.}$ $\text{Explanation:}$ $\text{Members of III period have somewhat higher electron gain enthalpy as compared to the corresponding members of second period, because of their small size.}$ $\text{O and S belong to VI A (16) group and Cl and F belong to VII A (17) group. Thus, the electron gain enthalpy of Cl and F is higher as compared to O and S.}$ $\text{Cl and F} > \text{O and S}$ $\text{Between Cl and F, Cl has higher electron gain enthalpy as in F, the incoming electron experiences a greater force of repulsion because of the small size of F atom.}$ $\text{Similar is true in case of O and S ie, the electron gain enthalpy of S is higher as compared to O due to its small size.}$ $\text{The value of electron gain enthalpy is as follows:}$ $\text{O} = -141 \text{ kJ mol}^{-1}; \text{S} = -200 \text{ kJ mol}^{-1}; \text{F} = -328 \text{ kJ mol}^{-1}; \text{Cl} = -349 \text{ kJ mol}^{-1}$ $\text{From O to Cl the value of electron gain enthalpy decreases because with the negative sign, the more negative value will be little and the less negative value will be high.}$ $\text{If an electron affinity order is asked then the order is Cl} > \text{F} > \text{S} > \text{O.}$ $\text{Thus, the correct order of electron gain enthalpy of given elements is : O}> \text{S} >\text{F}> \text{Cl}$ $\text{This corresponds to option 2: O} < \text{S} < \text{F} < \text{Cl (in terms of increasing negative values)}$