Given below are two statements : Statement I: Presence of large number of unpaired electrons in transition metal atoms results in higher enthalpies of their atomisation. Statement II: d_ xy = d_ xz = d_ yz In the light of the above statements, choose the correct answer from the options given below :
A. Both Statement I and Statement II are correct
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 [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 Both Statement I and Statement II are correct. Answer: Both Statement I and Statement II are correct
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