Classification of Elements Part 2

Concept:First ionization enthalpy depends on atomic size and electronic configuration stability.Electron gain enthalpy magnitude depends on atomic size and electron repulsion.Explanation:Statement I: Across period 2, ionization enthalpy generally increases.But nitrogen ($\mathrm{N}$) has stable half-filled $2p^3$ configuration.Oxygen ($\mathrm{O}$) has $2p^4$ with paired electron repulsion, making it easier to remove an electron.Thus, $\mathrm{IE}_1(\mathrm{O}) < \mathrm{IE}_1(\mathrm{N})$.Order: $\mathrm{C} < \mathrm{O} < \mathrm{N} < \mathrm{F}$ is correct.Statement I is true.Statement II: Down group 16, electron gain enthalpy becomes less negative due to increasing size.Oxygen is very small, causing strong repulsion to incoming electron, so its magnitude is less than sulphur.Sulphur has the most negative electron gain enthalpy in group 16.Order of magnitude: $\mathrm{S} > \mathrm{Se} > \mathrm{Te} > \mathrm{Po} > \mathrm{O}$ is correct.Statement II is true.Answer:Both Statement I and Statement II are true.Correct option: D.