Assertion: Manganese (atomic number 25) has a less favorable electron affinity than its neighbors on either side. Reason: The magnitude of an element’s electron affinity depends on the element’s valence shell electrons configuration.

Manganese has less favorable electron affinity than its neighbors on its either side because of its highly stable electronic configuration. Mn 5 2 3 4 Ar d s ,due to which it has 5 unpaired electrons, thus having maximum multiplicity. And the magnitude of the electron affinity of an element is based on its valence shell electronic configuration. Hence, option (b) is the correct answer.