Question

The no of possible ionisation potential for uni negetive oxide ion is

Answer 1

Answer:

First electron gain enthalpy for oxygen is negative (-141 kJ/mol) and second electron gain enthalpy is positive (+780 kJ/mol) as energy is required to overcome the force of repulsion between the electron and uninegative ion.

Hence, in the formation of oxide ion, O

2−

(g), first an exothermic reaction and then an endothermic reaction take place. Thus assertion (A) is true.

O

−

ion has a comparatively large size than an oxygen atom. An anion (formed by the gain of one or more electrons to the atom) is always larger than the corresponding atom.

Thus, reason (R) is true. But (R) is not the correct explanation of (A).