Which of the following represents the correct order of increasing electron gain enthalpy with negative sign for the elements O, S, F and Cl?

Options

A. `S lt O lt C1 lt F`
B. `C1 lt F lt O lt Si`
C. `O lt S lt F lt C1`
D. `F lt S lt O lt Si`

Answer

C

Explanation

Due to greater electronegativity of halogens over elements of group 16 the electron gain enthalpies of halogens (i.e., F and C1) are more negative than the corresponding element of group 16 (i.e., O and S) Further due to greater inter- electronic repulsions in the small size of elements of 2nd over 3rd period, the electron gain enthalpies of elements of 2nd period are less negative than the corresponding elements of the third period. Thus negative electron gain enthalpies increase in the order : `O(- 141 kJ mol^(-1) lt S (- 200 kJ mol^(-1)) lt F (- 328 kJ mol^(-1) ) lt C1 (- 349 kJ mol^(-1))` i.e., option ( c) is correct.