The formation of the oxide ion `O_(g)^(2-)` requires first an exothermic and
Channel: Doubtnut
Date: 19/01/2020

The formation of the oxide ion `O_(g)^(2-)` requires first an exothermic and then an endothermic step as shown below: `O_(g)+e^(-) rarr O_(g)^(-)`, `DeltaH=-142 kJ mol^(-1)` `O(g)+e rarr O_(g)^(2-)`, `DeltaH=844kJ mol^(-1)` This is because: