Verified Solution • 2025–26 Session
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QJEEM18Ch3abc: JEE Main 2018 Chemistry - Class 12 JEEM18Ch3abc Solution: The correct combination is :
The correct combination is :
Multiple Choice Options
- A [Ni(CN)4]2- tetrahedral ; [Ni(CO)4] paramagnetic
- B [Ni(Cl)4]2- paramagnetic ; [Ni(CO)4] tetrahedral
- C [Ni(Cl)4]2- square-planar ; [Ni(CN)4] 2- paramagnetic
- D [Ni(Cl)4]2- diamagnetic ; [Ni(CO)4] square-planar
Step-by-Step Verified Solution
[NiCl4]2– : Oxidation state of Ni in [NiCl4]2– = + 2
Cl– is a weak field ligand and cannot take part in pairing of electrons.
Hence, the complex is tetrahedral and paramagnetic with two unpaired electrons.
[Ni(CO)4] : Oxidation state of Ni in [Ni(CO)4] is zero. CO is a strong field ligand thus pairing of electrons takes place in d-orbitals.
Hence, the complex is tetrahedral and diamagnetic.
Cl– is a weak field ligand and cannot take part in pairing of electrons.
Hence, the complex is tetrahedral and paramagnetic with two unpaired electrons.
[Ni(CO)4] : Oxidation state of Ni in [Ni(CO)4] is zero. CO is a strong field ligand thus pairing of electrons takes place in d-orbitals.
Hence, the complex is tetrahedral and diamagnetic.