Given below are two statements : Statement I: Presence of large...

Statement I: The enthalpy of atomisation of transition metals depends on the strength of metallic bonding. A greater number of unpaired electrons in the d-orbitals leads to stronger metallic bonding, which results in a higher enthalpy of atomisation. Thus, Statement I is correct.

Statement II: $[Fe(H_2O)_6]^{3+}$ is an octahedral complex. In an octahedral crystal field, the d-orbitals split such that the $t_{2g}$ set of orbitals ($d_{xy}, d_{xz}, d_{yz}$) has lower energy than the $e_g$ set of orbitals ($d_{x^2-y^2}, d_{z^2}$). Therefore, $d_{xy} = d_{xz} = d_{yz} < d_{x^2-y^2} = d_{z^2}$.

$[Ni(Cl)_4]^{2-}$ is a tetrahedral complex because $Cl^{-}$ is a weak field ligand and the coordination number is $4$. In a tetrahedral crystal field, the splitting is reversed compared to the octahedral field. The $e$ set of orbitals ($d_{x^2-y^2}, d_{z^2}$) has lower energy than the $t_2$ set of orbitals ($d_{xy}, d_{xz}, d_{yz}$). Therefore, $d_{x^2-y^2} = d_{z^2} < d_{xy} = d_{xz} = d_{yz}$. Thus, Statement II is also correct.

Both Statement I and Statement II are correct.

Answer: Both Statement I and Statement II are correct