In which of the following processes, heat is neither absorbed nor released by a system?

Options

A. `Cl + e^(-) to Cl^(-)`
B. `O^(-) + e^(-) to O^(2-)`
C. `O^(2-) - e^(-) to O^(-)`
D. `Na^(+) + e^(-) to Na`

Answer

B

Explanation

Due to smaller size of O, gain in `e^(-)` causes ` e^(-) - e^(-) ` repulsion hence energy is required.