Verified Solution • 2025–26 Session moderate

QJEEM22Ch807e: JEE Main 2022 Chemistry - Class 12 JEEM22Ch807e Solution: The metal complex that is diamagnetic is (Atomic number:

The metal complex that is diamagnetic is (Atomic number: Fe,26;Cu,29)\mathrm{Fe}, 26 ; \mathrm{Cu}, 29)

Multiple Choice Options

  • A K3[Cu(CN)4]\mathrm{K}_{3}\left[\mathrm{Cu}(\mathrm{CN})_{4}\right]
  • B K2[Cu(CN)4]\mathrm{K}_{2}\left[\mathrm{Cu}(\mathrm{CN})_{4}\right]
  • C K3[Fe(CN)4]\mathrm{K}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{4}\right]
  • D K4[FeCl6]\mathrm{K}_{4}\left[\mathrm{FeCl}_{6}\right]

Step-by-Step Verified Solution

⇒K3[Cu(CN)4]\Rightarrow \mathrm{K}_{3}\left[\mathrm{Cu}(\mathrm{CN})_{4}\right] is diamagnetic

Cu(I)⇒d10\mathrm{Cu}(\mathrm{I}) \Rightarrow \mathrm{d}^{10} configuration ⇒\Rightarrow No unpaired electrons.

⇒K2[Cu(CN)4],K3[Fe(CN)4]\Rightarrow \mathrm{K}_{2}\left[\mathrm{Cu}(\mathrm{CN})_{4}\right], \mathrm{K}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{4}\right] and K4[FeCl6]\mathrm{K}_{4}\left[\mathrm{FeCl}_{6}\right] are paramagnetic in nature

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