CBSE 2026 · Region 4 · Set 1 · Q25 · 3 marks
When a coordination compound $\displaystyle \mathrm{CoCl}_{3} \cdot 6 \mathrm{NH}_{3}$ is mixed with excess of $\displaystyle \mathrm{AgNO}_{3}$ solution, $\displaystyle 3$ moles of AgCl are precipitated per mole of the compound. Write the structural formula of the complex, IUPAC name, its hybridisation and magnetic behaviour on the basis of valence bond theory.(b)How many geometrical isomers are possible in each of the following complexes?(I)$\displaystyle \left[\mathrm{Cr}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]^{3-}$(II)$\displaystyle \left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{3} \mathrm{Cl}_{3}\right]$(ii)$\displaystyle \left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}$ is an inner orbital complex whereas $\displaystyle \left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+}$ is an outer orbital complex. Why ? [Atomic number : $\displaystyle \mathrm{Co}=27, \mathrm{Ni}=28$ ](iii)Write the formula of Wilkinson catalyst and its use.
When a coordination compound $\displaystyle \mathrm{CoCl}_{3} \cdot 6 \mathrm{NH}_{3}$ is mixed with excess of $\displaystyle \mathrm{AgNO}_{3}$ solution, $\displaystyle 3$ moles of AgCl are precipitated per mole of the compound. Write the structural formula of the complex, IUPAC name, its hybridisation and magnetic behaviour on the basis of valence bond theory.
(b)
How many geometrical isomers are possible in each of the following complexes?
(I)
$\displaystyle \left[\mathrm{Cr}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]^{3-}$
(II)
$\displaystyle \left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{3} \mathrm{Cl}_{3}\right]$
(ii)
$\displaystyle \left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}$ is an inner orbital complex whereas $\displaystyle \left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+}$ is an outer orbital complex. Why ? [Atomic number : $\displaystyle \mathrm{Co}=27, \mathrm{Ni}=28$ ]
(iii)
Write the formula of Wilkinson catalyst and its use.
Marking-scheme solution
•
[Co(NH3)$\displaystyle 6$]Cl3
• Hexaamminecobalt(III) chloride
•
d2sp3
• diamagnetic
(b)
(I)
Nil / zero
(II)
$\displaystyle 2$
(ii)
NH3 being a strong field ligand pair up the unpaired electrons in Co3+ leaving two
d-orbitals empty for d2sp3 hybridization forming inner orbital complex.
Whereas it cannot pair up in Ni2+ as only one ‘d’ orbital is left empty after pairing
which is not possible and hence outer d-orbital is used. / Diagrammatic representation
(iii)
[(Ph3P)3RhCl]
Used for hydrogenation of alkene
Coordination CompoundsIsomerism in Coordination CompoundsApplyshort_answerhard
More from Coordination Compounds
- The Valence Bond Theory (VBT) explains the formation, magnetic behaviour and geometrical shapes of…2024 · asked 3×
- Which of the following ligands forms a chelate complex?2026 · asked 3×
- Write the IUPAC name of the complex [Pt(en) 2 Cl 2]^2+. Draw the structure of geometrical isomer of this…2025 · asked 3×
- The nature of bonding, structure of the coordination compound can be explained to some extent by valence bond…2024 · asked 3×
- Draw the geometrical isomers of [Co(en) 2 Cl 2]^2+. Which geometrical isomer of [Co(en) 2 Cl 2]^2+ is not…2023 · asked 3×
- In coordination compounds, metals show two types of linkages, primary and secondary. Primary valencies are…2023 · asked 3×
- Answer any three of the following questions: Explain the type of hybridization in [Fe(CN) 6]^3- on the basis…2023 · asked 3×
- Which of the following species cannot act as a ligand? Give reason. OH^-, NH 4^+, CH 3 NH 2, H 2 O The…2023 · asked 3×
CBSE Class 12 Chemistry past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.