Read the following statements carefully: I. The first ionization enthalpy of nitrogen is greater than that of oxygen. II. The electron gain enthalpy of fluorine is less negative than that of chlorine. III. The atomic radius of gallium is less than that of aluminium. IV. Among the isoelectronic species N ³⁻ , O ²⁻ , and F ⁻ , the ionic radius is largest for F ⁻ . How many of the given statements are correct?

Step-by-step solution

Statement I is correct: Nitrogen has a stable half-filled 2p orbital configuration ( 2s² 2p³ ), making its first ionization enthalpy higher than that of oxygen ( 2s² 2p⁴ ). Statement II is correct: Due to the small size of the fluorine atom, there is strong interelectronic repulsion in its relatively compact 2p subshell. Thus, its electron gain enthalpy is less negative than that of chlorine. Statement III is correct: The atomic radius of gallium (135 pm) is less than that of aluminium (143 pm) due to the poor shie