See image — AITS & Test Series Chemistry Question

💡 Solution & Explanation

Atom/Ion Complex Configuration No. of unpaired electrons Magnetic nature     2 8 2 4 Ni 3d NiCl     2 4 Ni CN      2 2 0 Paramagnetic Paramagnetic Diamagnetic     8 2 4 Ni 3d 4s Ni CO     2 0 Paramagnetic Diamagnetic