The atomic number of the central metal atom can be determined by the EAN rule.
Given : metal carbonyl is M(CO)x where, M = metal x = 4
Thus, the metal carbonyl is M(CO)4The CO is a neutral ligand, having a lone pair of electrons.
It is a monodentate ligand.
Thus, electrons donated per ligand per donor atom = 2 Number of electrons donated by 4 CO molecule = 2 × 4 = 8 electrons.
According to the EAN rule, the ligands in the coordination sphere of a transition metal complex must provide the necessary number of electrons that will give the central metal ion the electronic configuration of a noble gas.
We know that,Effective atomic number (EAN) for M = Atomic number of M (Z) + Number of electrons donated by 4COLet EAN be 36 (Atomic number of krypton, a rare gas).
36 = Z + 8Z = 36 - 8 = 28
Therefore,Atomic number of M = 28
Hence, the correct option is (D).
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)

Cobalt chloride when dissolved in water forms pink colored complex $X$ which has octahedral geometry. This solution on treating with cone $HCl$ forms deep blue complex, $\underline{Y}$ which has a $\underline{Z}$ geometry $X, Y$ and $Z$, respectively, are
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)
A black body is at a temperature of 2880 K. The energy of radiation emitted by this body with wavelength between 499 nm and 500 nm is U1, between 999 nm and 1000 nm is U2 and between 1499 nm and 1500 nm is U3. The Wien's constant, b = 2.88×106 nm-K. Then,