Board exam

Arrange the following compounds as directed : (any Two)

1. (i)
   In decreasing order of basic strength in aqueous solution : C₂H₅NH₂, (C₂H₅)₂NH, (C₂H₅)₃N
2. (ii)
   In increasing order of solubility in water : (C₂H₅)₂ NH, C₂H₅NH₂, C₆H₅NH₂
3. (iii)
   In decreasing order of their pKb values : C₆H₅NH₂, C₂H₅NH₂, NH₃

Write the Nernst equation for the following cell reaction : Zn(s) + Cu²⁺ (aq) → Zn²⁺ (aq) + Cu(s) How will the E₍cell₎ be affected when concentration of

1. (i)
   Cu²⁺ ions is increased and
2. (ii)
   Zn²⁺ ions is increased ?

Following ions of 3d-transition series are given : Ti⁴⁺, V³⁺, Cr³⁺, Mn³⁺ (Atomic number : Ti = 22, V = 23, Cr = 24, Mn = 25) Identify the ion which is

1. (i)
   most stable in aqueous solution.
2. (ii)
   a strong oxidising agent.
3. (iii)
   colourless in aqueous solution. Give suitable reason in each.

(a)

1. (i)
   On the basis of crystal field theory, write the electronic configuration for d⁴ ion if Δ₀ < P.
2. (ii)
   Using valence bond theory, predict the hybridization and magnetic character of [Ni(CN)₄]²⁻. (Atomic number of Ni = 28)
3. (iii)
   Write the formula of the following complex using IUPAC norms : Dichloridobis (ethane-1,2-diamine) cobalt (III) OR (b) When a co-ordination compound NiCl₂·6H₂O mixed with AgNO₃, 2 moles of AgCl are precipitated per mole of the compound. Write (i) Structural formula of the complex. (ii) Secondary valency of ‘Ni’ in the complex. (iii) IUPAC name of the complex.

(a) Illustrate the following reactions giving suitable example in each case :

1. (i)
   Gabriel phthalimide synthesis.
2. (ii)
   Carbylamine reaction.
3. (iii)
   Hoffmann bromamide degradation reaction. OR (b) Write the structures of A, B and C in the following reactions : (i) CH₃CH₂Cl —KCN→ A —LiAlH₄→ B —HNO₂, 0 °C→ C (ii) CH₃COOH —NH₃, Δ→ A —(a) LiAlH₄ (b) H₂O→ B —C₆H₅SO₂Cl→ C

(a) Account for the following :

1. (i)
   Transition elements have higher enthalpies of atomisation.
2. (ii)
   Separation of a mixture of Lanthanoid elements is difficult.
3. (iii)
   The E°₍M²⁺/M₎ value for copper is positive. OR (b) Define transition elements. Which of the d-block elements may not be regarded as the transition elements ? Why transition metals generally form coloured compounds ?