Question

The correct order of negative value of electron gain enthalpy is:
[0.77 Mark]

• A. $Te>Se>S>O$
• B. $S>Se>Te>O$
• C. $O>S>Se>Te$
• D. $S>O>Se>Te$

Answer 1

The correct option is B $S>Se>Te>O$

$O$ has exceptionally smaller value of electron affinity (minimum in family) due to smaller atomic size than sulphur (weaker electron-electron repulsion is larger $3p$-subshell)

Element	${\Delta }_{eg}H\text{(kJ/mol})$
O	-141
S	-200
Se	-195
Te	-190