JEE Main · 2023 · Shift-ImediumBOND-099

In which of the following processes does the bond order increase and paramagnetic character change to diamagnetic?

Chemical Bonding · Class 11 · JEE Main Previous Year Question

Question

In which of the following processes does the bond order increase and paramagnetic character change to diamagnetic?

Options
  1. a

    O2→O2+\mathrm{O_2 \rightarrow O_2^+}

  2. b

    O2→O22−\mathrm{O_2 \rightarrow O_2^{2-}}

  3. c

    NO→NO+\mathrm{NO \rightarrow NO^+}

    ✓
  4. d

    N2→N2+\mathrm{N_2 \rightarrow N_2^+}

Correct Answerc

NO→NO+\mathrm{NO \rightarrow NO^+}

Detailed Solution

🧠 Two conditions must both be satisfied: (i) bond order increases, (ii) magnetic character changes from paramagnetic to diamagnetic.

| Process | BO change | Magnetic change | |---|---|---| | \ceO2−>O2+\ce{O2 -> O2+} | 2 → 2.5 ↑ | paramagnetic → paramagnetic (still 1 unpaired e) ✗ | | \ceO2−>O22−\ce{O2 -> O2^{2-}} | 2 → 1 ↓ | paramagnetic → diamagnetic, but BO decreases ✗ | | \ceNO−>NO+\ce{NO -> NO+} | 2.5 → 3 ↑ ✓ | paramagnetic → diamagnetic ✓ | | \ceN2−>N2+\ce{N2 -> N2+} | 3 → 2.5 ↓ | diamagnetic → paramagnetic ✗ |

🗺️ NO (15e) has 1 unpaired electron in π2p∗\pi^*_{2p} → paramagnetic. \ceNO+\ce{NO+} (14e, isoelectronic with \ceN2\ce{N2}) has all electrons paired → diamagnetic. Bond order 2.5 → 3 ✓.

Answer: (c) \ceNO−>NO+\boxed{\text{Answer: (c) } \ce{NO -> NO+}}

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