\({ }_{22} \mathrm{Ti}-{ }_{18}[\mathrm{Ar}] 4 \mathrm{s}^{2} 3 \mathrm{d}^{2} / {}_{21}\mathrm{Sc}-{ }_{18}[\mathrm{Ar}] 4 \mathrm{~s}^{2} 3 \mathrm{~d} \)
\({ }_{22} \mathrm{Ti}^{3+}-{ }_{18}[\mathrm{Ar}] 3 \mathrm{~d}^{1} /{ }_{18} \mathrm{Sc}^{3+}{ }_{18}[\mathrm{Ar}] 3 \mathrm{~d}^{0}\)
(i) In this complex the central metal ion is Ti³⁺, which has d¹ configuration. This single electron occupies one of the t_2g orbitals in the octahedral aqua ligand field. When white light falls on this complex the electron absorbs light and promotes itself to e_g level. The spectral data show the absorption maximum is at 20000 cm^-1 corresponding to the crystal field splitting energy \(\left(\Delta_{o}\right)\) 239.7 kJmol^-1. The transmitted colour associated with this absorption is purple and hence the complex appears purple in colour.
(ii) Thus in \(\left[\mathrm{Ti}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+} \mathrm{d}-\mathrm{d}\) transition takes place.
(iii) But in \(\left[\mathrm{Sc}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+} \mathrm{Sc}^{3+}\) has the outer electronic configuration of 3d⁰ where d-d transition is not possible and it is colourless.

(i) \(\mathrm{Mg}\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right) \mathrm{Cl}_{5}\right]^{2-} \rightleftharpoons \mathrm{Mg}^{2+}+\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right) \mathrm{Cl}_{5}\right]^{2-} (2 ions)\)
(ii) \(\begin{aligned} {\left[\mathrm{Cr}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}_3\left[\mathrm{CoF}_6\right]_2 \rightleftharpoons 3\right.} & {\left[\mathrm{Cr}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}\right]^{2+} } \\ & (5 \text { ions }) \end{aligned}\)\(+2\left[\mathrm{CoF}_6\right]^{3-}\)
(iii) \(\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{3} \mathrm{Cl}_{3}\right]= \text{ No ions}\)
If no of ions increases, molar conductivity increases molar conductivity of the complex also INCREASES.
\(\therefore\) The order of the given compound is
[Cr(NH₃)₃Cl₃]<Mg[Cr(NH₃)₃Cl₃] < [Cr(NH₃)₅Cl₃] [CoF₆]₂
  (No ion)          (2 ions)                    (5 ions)

a) potassiumhexacyanidoferrate(II) - Potassiumhexacyanidoferrate(II) - K₄[Fe(CN)₆]
b) Pentacarbonyliron(0) - [Fe(CO)₅]
c) Pentaamminenitrito −kNcobalt(III)ion - [Co(NH₃)₅(NO₂)]²⁺
d) Hexaamminecobalt(III) Sulphate  - [CO(NH₃)₆](SO₄)₃
e) Sodiumtetrafluoridodihydroxidochromate(III)  - Na₂[CrF₄(OH)₂]

i) Na₂[Ni(EDTA)] - Sodium 2, 2', 2",2'" - (ethane-1,2 diyldinitrilo tetraacetatonickelate)(II)
ii) [Ag(CN)₂]^- - Dicyanido-kC-argentate (I) ion
iii) [CO(en)₃]₂(SO₄)₃ - Tris (ethane 1, 2 diamine)cobalt (III) sulphate
iv) [CO(ONO)(NH₃)₅]²⁺ - Pentaamminenitrito - KO cobalt (III) ion
v) [Pt(NH₃)₂Cl(NO₂)] - Diammainechloridonitro - kN - platinum (II)

[Co (en)₂ Cl₂]⁺ This is an octahedral complex