LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
M.Sc. DEGREE EXAMINATION – CHEMISTRY
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SECOND SEMESTER – APRIL 2007
CH 2809 – CHEMISTRY OF MAIN GROUP ELEMENTS
Date & Time: 19/04/2007 / 1:00 – 4:00 Dept. No. Max. : 100 Marks
Part-A
Answer all questions. Each question carries two marks
- List some differences between chemical properties of main group elements and sub-group elements.
- Why do some ionic compounds like BaSO4 have poor solubility in water?
- How is VSEPR model different from VBT?
- Explain LCAO.
- How does the geometry of a molecule influence its stability?
- Illustrate anti Markownickoff addition of BH2 during hydroboration.
- What are silyl amines? How are they prepared?
- Differentiate metalloboranes and metallocarboranes.
- Illustrate the contrasting tendency of benzene and borazine toward addition reactions.
- What are cyclic phosphazane? Give the synthesis of one such compound.
Part-B
Answer Eight questions. Each question carries five marks
- What are the differences in the properties of E-Cl bond in CCl4 and PbCl4? Give reasons.
- Give the significance of electronegativity and electronegativity difference citing examples.
- Explain characteristic reactions of (i) electron-rich and (ii) electron-deficient molecules.
- Give a brief account of interhalogen compounds.
- Why does Xe alone form compounds among noble gases? Why does it combine only with some halogens and oxygen?
- Why is SO2 a good oxidizing agent while SeO2 and TeO2 are not?
- Give an account of the synthesis and structural aspects of isopoly molybdates and tungstates.
- Explain the method of synthesizing two-cage phosphorous sulfides.
- What are cyclic metaphosphates? Give an account of their synthesis and structural aspects.
- Write a note on linear polyphosphazenes.
- Explain the utility of organochlorides of nonmetals for catenation by coupling.
- Cite an account of the synthesis of two homocyclic inorganic rings.
Part-C
Answer Four questions. Each question carries ten marks
- Draw MO energy level diagram for (i) a highly ionic and (ii) a highly covalent diatomic molecules and explain the nature of bonding and anti-bonding orbitals.
- Discuss the unique chemical properties of boron and nitrogen group elements and their compounds.
- Discuss allotropes of carbon and their properties.
- Explain the solvolysis reactions of nonmetal halides and organohydrides.
- Give a brief account of the preparation of polyhedral borane anions. Explain the structure and bonding in these compounds with the help of PSEPT.
- (a) Give an account of the formation and structural aspects of heteropoly anions.
(b) Give an account of the reactivity and utility of non-metal fluorides as
fluorinating agents.
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