Wednesday, 18 March 2015

CHEMISTRY – 2005 PAPER- I, SECTION – A, SECTION – B

                       Time allowed: three Hours    maximum marks: 200
Candidates should attempt question 1 and 5 which are compulsory, and any Three of the following questions selecting at least one question from each section.

SECTION – A

1.       Answer any FOUR of the following:-
(a)    What are the four quantum numbers? Show that these are not same for Cu atom,
(b)   Explain the terms order and molecularity of a reaction by considering the reaction of eater hydrolysis.
(c)    Draw the shapes of s, p, and d orbital’s, show their directional characteristics
(d)   Explain why H₂O exists as solid ice, liquid as well as gas whereas H₂ S exists as gas only.
(e)   What are the crystal types of NaCI and CsCI and explain the difference.

2.       (a) derive an expression for the energy of  particle in a box ( one dimensional only)
                               (b) Draw molecular orbital diagram of CO and its valence bond picture explaining its bond order and back bonding character.

3.       (a) Explain the difference between a conductor, semiconductor and insulator on the basis of band theory. How additions of an impurity affects the behavior of a pure metal/ crystal?

                              (b)  Derive expressions for work done against:

(i)                  Constant external pressure and
(ii)                Isothermal reversible expansion of n ideal gas showing that the work done depends on initial and final states only.

4.       (a) In want respects phase diagram of binary system differs from one component system considering a suitable example?
                             (b) What is electrochemical series? Explain how it helps to determine reducing and oxidizing properties of specie. Calculate e.m.f. of an electrochemical cell
 Mg(s) + Cu ²⁺ (aq)    → Mg² (aq) + Cu(S)
Given that half cell potentials of
Mg² (aq) + 2e → Mg(s) and
Cu² (aq) + 2e   → Cu (s)
Are – 2.360 and 0.337 V respectively.

SECTION – B
5.       Answer any FOUR of the following:
(a)    What is the difference between adsorption and absorption? Explain with a suitable example foe each.
(b)   Explain photosynthesis and show with the help of a suitable experiment that CO₂, H₂O and sunlight are essential.
(c)    Show that ammonia behaves as solvent with suitable examples for neutralization and complex formation reactions.
(d)   In what respect lanthanides are different than actimides especially with regard to their occurrence, and oxidation states?
(e)   Discuss the structure of Ni (CO)₄

6.       (a)  What are the various postulates of crystal field theory? Draw the crystal field splitting of 3d orbitsals in presence of six ligands to form octahedral geometry. Calculate crystal field stabilization energy and magnetic moments for d⁴ and d⁵ configurations in presence of H₂O and CN- as ligands.
                             (b)  Write brief notes on the following with suitable example data: - (i) Chain reactions (ii) Lanthanide contraction.

7.       (a) What are the various types of metal carbonyls? Explain the bonding characteristics of metal carbonyls. Give an example each for mono, di- and tricarbonyls and draw their structures.
                                (b) What do you understand by thermodynamic and kinetic stability of complexes? Explain the terms ‘inert’ and ‘labile’ with a suitable example for each.

8.       (a) explain the following terms briefly with suitable example:-
(i)                  Super acids
(ii)                Metal atom clusters.
                                  (b)   What is first order reaction? Derive an expression for half life of first order reaction. Draw the nature of plot between logs [N₂ O₄] against time in the first order decomposition of N₂O₄.

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