Which of the following processes involves absorption of energy? — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Step 1: The addition of the first electron to a neutral gaseous non-metal atom (like S or Cl) is generally an exothermic process because of the nuclear attraction. Step 2: Gaining a second electron requires adding a negatively charged electron to an already negatively charged anion (S^-). Step 3: This process is dominated by strong electrostatic repulsion between the anion and the incoming electron, requiring an absorption of energy to proceed. Thus, option (b) is endothermic.