Answer the following: With reference to Valence Bond Theory (VBT), answer the following questions…
Answer the following:
(a)[2.0]
With reference to Valence Bond Theory (VBT), answer the following questions regarding the complex ion $[\text{Cr}(\text{NH}_3)_6]^{3+}$.
(1) What is the oxidation number of chromium in the complex?
(2) State the magnetic behaviour of the complex.
(3) How many unpaired electrons are there in the complex?
(4) State the type of hybridisation of the central metal atom.
(b)[2.0]
The coordination complex $\text{CoNO}_2\text{Cl} \cdot 5\text{NH}_3$ exists in two isomeric forms ‘P’ and ‘Q’. Isomer ‘P’ reacts with $\text{AgNO}_3$ solution to give white precipitate whereas ‘Q’ does not give any precipitate with $\text{AgNO}_3$ solution.
(1) Write the structural formula of isomers ‘P’ and ‘Q’.
(2) Name the type of isomerism involved.
(c)[1.0]
Explain why an aqueous solution of potassium hexacyanidoferrate(II) does not give the test of ferrous ion.
Answer
Answer (a)
AIWritten by AI (gemini) - it can contain mistakes.
(1) Oxidation number of chromium = +3
(2) Magnetic behaviour = Paramagnetic
(3) Number of unpaired electrons = 3
(4) Type of hybridisation = $d^2sp^3$
Answer (b)
AIWritten by AI (gemini) - it can contain mistakes.
(1) Structural formula of isomers 'P' and 'Q':
Isomer 'P': $[\text{Co}(\text{NH}_3)_5(\text{NO}_2)]\text{Cl}$
Isomer 'Q': $[\text{Co}(\text{NH}_3)_5\text{Cl}]\text{NO}_2$
(2) Type of isomerism involved: Ionisation isomerism
Answer (c)
AIWritten by AI (gemini) - it can contain mistakes.
Potassium hexacyanidoferrate(II), $\text{K}_4[\text{Fe}(\text{CN})_6]$, is a complex compound that ionizes in aqueous solution to give potassium ions and complex hexacyanidoferrate(II) ions:
$\text{K}_4[\text{Fe}(\text{CN})_6] \xrightarrow{\text{aq}} 4\text{K}^+ + [\text{Fe}(\text{CN})_6]^{4-}$
The coordination complex ion $[\text{Fe}(\text{CN})_6]^{4-}$ is extremely stable and does not dissociate to liberate free ferrous ions ($\text{Fe}^{2+}$). Because tests for ferrous ions require free $\text{Fe}^{2+}$ in solution, the solution does not respond to these tests.
From ISC 2026 Chemistry Paper 1, question 21(i).