The process requiring absorption of energy is : — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Step 1: The process of forming a gaseous anion from a neutral atom represents electron gain. For halogens (F, Cl) and Hydrogen (H), this process is exothermic (releases energy). Step 2: Nitrogen has an exceptionally stable, half-filled 2p3 configuration, and its compact size results in significant electron-electron repulsion if another electron is added. Step 3: Consequently, adding an electron to gaseous Nitrogen requires overcoming these stable electronic conditions, making it an endothermic process that absorbs energy (option a).