Periodic Trends In Properties Of Elements

A. Nitrogen atom: Nitrogen is in group 15. Nitrogen has the highest ionization enthalpy in group 15 due to its half-filled p orbitals providing extra stability. Thus, A-III.

B. Fluorine molecule: Fluorine is the most electronegative element and a powerful oxidizing agent. F₂ is the strongest oxidizing agent among the given options. Thus, B-IV.

C. Oxygen molecule: Oxygen (O₂) is paramagnetic because it has two unpaired electrons in its antibonding molecular orbitals. Thus, C-I.

D. Xenon atom: Xenon is a noble gas in group 18. It is the most reactive element in group 18 due to its larger size and lower ionization energy compared to other noble gases in the same group, making it more susceptible to forming compounds. Thus, D-II.