Facial (fac) and meridional (mer) isomers are types of geometric isomers found in octahedral complexes with the general formula \([MA_3B_3]\). In these complexes, three identical ligands can either be adjacent to each other forming a 'facial' configuration or adjacent to form a 'meridional' configuration.
Let's analyze why the other complexes do not show fac-mer isomerism:
Thus, the correct complex exhibiting facial-meridional isomerism is \([Co(NH_3)_3Cl_3]\).
To determine which complex shows facial-meridional isomerism, we first need to understand what these terms mean:
Now, let's evaluate the given complexes:
\([Co(NH_3)_3Cl_3]\): This complex can display facial-meridional isomerism as it is an octahedral complex with three amine ligands and three chloride ligands, allowing for both fac-arrangement (three Cl or NH3 occupy one face) and mer-arrangement (three Cl or NH3 in a plane).
\([Co(NH_3)_4Cl_2]^+\): This complex cannot exhibit this isomerism as it lacks three identical ligands that could form a face.
\([Co(en)_3]^{3+}\): This complex is homoleptic, consisting of three ethylenediamine (\(en\)) ligands that do not allow for facial-meridional distinction.
\([Co(en)_2Cl_2]^+\): Similar to the above, this complex cannot show facial-meridional isomerism as it has only two Cl ions, preventing the formation necessary for fac-mer isomerism.
Thus, the correct complex that shows facial-meridional isomerism is:
\([Co(NH_3)_3Cl_3]\)
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
| List I (Substances) | List II (Element Present) |
| (A) Ziegler catalyst | (I) Rhodium |
| (B) Blood Pigment | (II) Cobalt |
| (C) Wilkinson catalyst | (III) Iron |
| (D) Vitamin B12 | (IV) Titanium |
| List-I (Complex ion) | List-II (Spin only magnetic moment in B.M.) |
|---|---|
| (A) [Cr(NH$_3$)$_6$]$^{3+}$ | (I) 4.90 |
| (B) [NiCl$_4$]$^{2-}$ | (II) 3.87 |
| (C) [CoF$_6$]$^{3-}$ | (III) 0.0 |
| (D) [Ni(CN)$_4$]$^{2-}$ | (IV) 2.83 |
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,