Import Question JSON

$\text{HINT: Generally down the group electron gain enthalpy decreases.}$ $\text{Explanation:}$ $\text{As we move from Cl to I, the electron gain enthalpy (i.e., energy released in electron gain) become less and less negative due to a corresponding increase in the atomic size.}$ $\text{However, the electron gain enthalpy of F is less negative than that of Cl due to its small size.}$ $\text{Thus, the negative electron gain enthalpy follows the order : F < Cl > Br > I}$ $\text{Detailed explanation:}$ $\text{Electron gain enthalpy is the energy change when an electron is added to a neutral gaseous atom to form an anion.}$ $\text{Generally, electron gain enthalpy becomes less negative (decreases) down a group due to:}$ $\text{1. Increase in atomic size}$ $\text{2. Decrease in nuclear attraction for the incoming electron}$ $\text{However, fluorine is an exception because:}$ $\text{1. F atom is very small in size}$ $\text{2. The incoming electron experiences strong electron-electron repulsion in the compact 2p orbital}$ $\text{3. This makes it less favorable to add an electron to F compared to Cl}$ $\text{Therefore, Cl has the highest (most negative) electron gain enthalpy among halogens, followed by F, then Br, and finally I.}$ $\text{The correct order is: F < Cl > Br > I}$