Question

Electron affinity is positive when______.

• A. O${}^{-}$ is formed from $O$
• B. $O^{2-}$ is formed from $O^{-}$
• C. $O^{+}$ is formed from $O$
• D. electron affinity is always a negative value

Answer 1

The correct option is B $O^{2-}$ is formed from $O^{-}$

Electron affinity is energy releases when one atom accepts electron so due to existing electron repulsion, when $O^{2-}$ is formed from $O^{-}$, this have positive electron affinity.