Coordination Compounds

The number of unpaired electrons present in the $\mathrm{Fe}^{2+}$ ion (atomic number of Fe = 26) in its ground state is

Which of the following sequences of hybridisation, geometry and magnetic nature are correct for the given coordination compounds ? A. $\mathrm{[NiCl_4]^{2-}}$ – $sp^3$, tetrahedral, paramagnetic B. $\mathrm{[Ni(NH_3)_6]^{2+}}$ – $sp^3d^2$, octahedral, paramagnetic C. $\mathrm{[Ni(CO)_4]}$ – $sp^3$, tetrahedral, paramagnetic D. $\mathrm{[Ni(CN)_4]^{2-}}$ – $dsp^2$, square planar, diamagnetic. Choose the correct answer from the options given below :

An excess of $\mathrm{AgNO_3}$ is added to 100 mL of a 0.05 M solution of tetraaquadichloridochromium (III) chloride. The number of moles of AgCl precipitated will be ______ $\times10^{-3}$. (Nearest integer)

Given below are two statements : Statement I : Among Zn, Mn, Sc and Cu, the energy required to remove the third valence electron is highest for Zn and lowest for Sc. Statement II : The correct order of the following complexes in terms of CFSE is $\mathrm{[Co(H_2O)_6]^{2+}<[Co(H_2O)_6]^{3+}<[Co(en)_3]^{3+}}$. In the light of the above statements, choose the correct answer from the options given below :

Which of the following complexes will show coordination isomerism ? A. $\mathrm{[Ag(NH_3)_2][Ag(CN)_2]}$ B. $\mathrm{[Co(NH_3)_6][Cr(CN)_6]}$ C. $\mathrm{[Co(NH_3)_6][Co(CN)_6]}$ D. $\mathrm{[Fe(NH_3)_6][Co(CN)_6]}$ E. $\mathrm{[Co(NH_3)_6][Fe(CN)_6]}$ Choose the correct answer from the options given below :

Match the LIST-I with LIST-II. LIST-I (Complex ion): A. $\mathrm{[Cr(H_2O)_6]^{2+}}$ B. $\mathrm{[Co(H_2O)_6]^{2+}}$ C. $\mathrm{[Cu(H_2O)_6]^{2+}}$ D. $\mathrm{[Mn(H_2O)_6]^{2+}}$. LIST-II (Calculated spin only magnetic moment (BM)): I. 3.87 II. 5.92 III. 4.90 IV. 1.73. Choose the correct answer from the options given below:

Consider the metal complexes $\mathrm{[Ni(en)_3]^{2+}}$ (A), $\mathrm{[NiCl_4]^{2-}}$ (B) and $\mathrm{[Ni(NH_3)_6]^{2+}}$ (C). Choose the CORRECT option by considering the number of unpaired electrons present in (A), (B) and (C) respectively and the order of frequency of absorption.

The correct statements about metal carbonyls are A. The metal-carbon bonds in metal carbonyls possess both $\sigma$ and $\pi$-character. B. Due to synergic bonding interactions between metal and CO ligand, the metal-carbon bond becomes weak. C. The metal-carbon $\sigma$ bond is formed by the donation of lone pair of electrons on the carbonyl carbon into a vacant orbital of metal. D. The metal-carbon $\pi$ bond is formed by the donation of electrons from filled d-orbital of metal into vacant $\pi^*$ orbital of CO. Choose the correct answer from the options given below:

Given below are two statements: Statement I: Each electron in $e_g$ orbitals destabilizes the orbitals by $+0.6\,\Delta_o$ and each electron in the $t_{2g}$ orbitals stabilizes the orbitals by $-0.4\,\Delta_o$ in an octahedral field on the basis of crystal field theory. Statement II: All the d - orbitals of the transition metals have the same energy in their free atomic state but when a complex is formed the ligands destroy the degeneracy of these orbitals on the basis of crystal field theory. In the light of the above statements, choose the correct answer from the options given below

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 : $d_{xy}=d_{xz}=d_{yz}<d_{x^2-y^2}=d_{z^2}$ and $d_{x^2-y^2}=d_{z^2}<d_{xy}=d_{xz}=d_{yz}$ are the d-orbital splittings in $[\mathrm{Fe(H_2O)_6}]^{3+}$ and $[\mathrm{Ni(Cl)_4}]^{2-}$ complex ions respectively. In the light of the above statements, choose the correct answer from the options given below :