Question

In which of the following options the species changes from paramagnetic to diamagnetic and bond order increases.

• A. \(N_2→N_{2}^{+}\)
• B. \(O_2→O_{2}^{+}\)
• C. \(NO→NO^+\)
• D. \(O_2→O^+\)

Answer 1

The Correct Option is C

To determine which species changes from paramagnetic to diamagnetic and experiences an increase in bond order, let's analyze each option:

1. \(N_2 \to N_{2}^{+}\)
   • Magnetic Property: \(N_2\) is diamagnetic (all electrons paired). \(N_{2}^{+}\) still remains diamagnetic because the unpaired electron is removed from the non-bonding orbitals.
   • Bond Order: The bond order of \(N_2\) is 3, and for \(N_{2}^{+}\), the bond order becomes 2.5 (decreases).
2. \(O_2 \to O_{2}^{+}\)
   • Magnetic Property: \(O_2\) is paramagnetic (due to two unpaired electrons in \(\pi^*\) orbitals). \(O_{2}^{+}\) remains paramagnetic as it still has one unpaired electron.
   • Bond Order: The bond order of \(O_2\) is 2, and for \(O_{2}^{+}\), the bond order increases to 2.5.
3. \(NO \to NO^+\) [Correct Answer]
   • Magnetic Property: \(NO\) is paramagnetic with one unpaired electron. \(NO^+\) is diamagnetic as the removal of an electron pairs up all remaining electrons.
   • Bond Order: The bond order of \(NO\) is 2.5, and for \(NO^+\), it increases to 3.
4. \(O_2 \to O^{+}\)
   • Magnetic Property: \(O_2\) is paramagnetic. \(O^{+}\), if considered to exist as a single charged oxygen, is a distinct situation and does not naturally follow typical molecular orbital calculations as it becomes a monoatomic oxygen rather than a molecular species.
   • Moreover, the bond order concept is not directly applicable to single atoms in the same way as it is to molecular species.

Thus, the option \(NO \to NO^+\) is correct as it transitions from paramagnetic to diamagnetic, and its bond order increases from 2.5 to 3.