The type of hybridisation and the spin only magnetic moment for the complex [ Ni ( CO )₄] are respectively:

Step-by-step solution

The central metal atom is Nickel (Ni) with atomic number 28. The electronic configuration of Ni is [Ar] 3d⁸ 4s² . In the complex [Ni(CO)₄] , the oxidation state of Ni is 0, as CO is a neutral ligand. The configuration remains [Ar] 3d⁸ 4s² . CO is a strong field ligand, which causes the pairing of electrons in the 3d orbital. The two electrons from the 4s orbital are promoted to the 3d orbital to complete the 3d¹⁰ configuration, leaving the 4s and 4p orbitals vacant. The four CO ligands donate electron pairs into on