The element, which has zero electron affinity in the 3rd period is-

Correct option is B

The correct answer is (b) Ar (Argon).
· Argon, being a noble gas, has a complete outer electron shell, making it highly stable.
· As a result, it has zero electron affinity, meaning it does not readily accept an additional electron.
Additional Knowledge:
· Al (Aluminium): Aluminium has a positive electron affinity, though it's relatively low.
· S (Sulfur): Sulfur has a relatively high electron affinity because it gains stability by accepting an electron.
· P (Phosphorus): Phosphorus has a positive electron affinity, although it's not as high as Sulfur.