Which one of the following ionic species has the greatest proton affinity to form stable compound?

Options

(a) NH₂⁻
(b) F⁻
(c) I⁻
(d) HS⁻

Correct Answer:

NH₂⁻

Explanation:

Proton affinity decreases in moving across the period from left to right due to increase in charge, within a group the proton affinities decreases from top to bottom. Nitrogen family > Oxygen family > Halogens