Question

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> When the first electron gain enthalpy $\left({\Delta }_{eg}H\right)$ of oxygen is $-141kJ/mol,$ its second electron gain enthalpy is:

JEE MAIN - 2019

• A. A more negative value than the first
• B. A positive value
• C. Negative, but less negative than the first
• D. Almost the same as that of the first

Answer 1

The correct option is B A positive value

Second electron gain enthalpy is always positive for any element, as energy has to be supplied to overcome the repulsion betwen the anion and the incoming electron.

$\underset{\left(g\right)}{O^{-}}+e^{-}\to \underset{\left(g\right)}{O^{2-}};{\Delta }_{eg}H=\text{positive}$
C is the correct option