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             LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

LM 30

SECOND SEMESTER – APRIL 2006

                                     CH 2809 – CHEMISTRY OF MAIN GROUP ELEMENTS

 

 

Date & Time : 21-04-2006/FORENOON     Dept. No.                                                       Max. : 100 Marks

Part-A

Answer all questions. Each question carries two marks

1. Both Li and Mg can be used to remove N₂ from other gases. Rationalize.
2. What are electrides? Cite an example.
3. Europium is frequently found in nature in group II minerals. Comment.
4. Compounds of alkaline earth metal ions are colorless, but [Be(bpy)(C₂H₅)₂] is bright red in color. Account for this observation.
5. What are pyrazaboles? Cite an example.
6. Cite the cyclohexane chair conformational analogue of phosphinoborane.
7. What are silanes? How do they act as a strong reducing agents for halogens?
8. What is ZSM-5 catalyst? Mention any two applications.
9. What is the basic unit of silica present in pyroxene mineral? Draw its structure.
10. Mention the general trend observed in the hydrolysis of interhalogen compounds.

Part-B

Answer eight questions. Each question carries five marks

11. Explain the structure of B₅H₉ using PSEPT theory.
12. Give an account of the preparation, properties, and structure of C₂B₁₀H₁₂.
13. Write brief notes on (a) silylamines and (b) inorganic rubber.
14. Explain the role of zeolites as molecular sieves.

15a.  Explain the principle involved in the qualitative estimation of CO by using I₂O₅.

1. Complete the following reactions: I₂O₅ + H₂S  ?; I₂O₅ + HCl  ?

I₂O₅ + F₂BF₃   ?

16. Explain the synthesis of linear phosphazenes and their reactivity toward amines, alkoxides, aryloxides, and organometallic reagents.
17. Give an account of hexagonal and cubic boron nitrides and their analogy toward graphite and diamond.
18. Give a brief account of natutrally occurring azamacrocycles.
19. Explain the chlorinating and oxidising reactions of any two oxides of chlorine.
20. Give an account of the chemistry of phosphorus compounds with P-P double bonds.
21. Give an account of the synthesis of aluminium alkyls and their synthetic importance. Comment upon the structures of aluminium alkyls and aluminium aryls.
22. How is phosphorus sulfides prepared? Depict their cyclic structures.

Part-C

Answer four  questions. Each question carries ten marks

23. Discuss the bonding in boranes. How can this be extended to cover higher boranes?

24a.  Explain the polyhedral rearrangements of closo-carboranes.                             (5)

1. Explain the preparation, properties, and structure of borazine.                         (5)

25a.  Give a brief account of the chemistry of oxohalogen fluorides.                       (7)

1. Write a note on heteropoly blues.                                                                      (3)

26a.  Explain the special equipments and fundamental techniques employed

in the synthesis of main group nonmetal compounds.                                       (6)

1. Explain the use of hexamethyldisilazane as a silylating agent for organic and inorganic compounds with examples. (4)

27a.  Give an account of naturally occurring ionophores and their interaction with the alkali and alkaline earth metal ions.                                                                    (6)

1. Explain the mechanism of ion transport across  cell membranes.                      (4)

28a.  Explain the synthesis, reactivity, and structural aspects of rings and cages involving

Si-Si multiple bonding.                                                                                      (6)

1. Give an account of heterocyclic inorganic ring systems involving Si-O and N-S bondings.                                                                                                       (4)

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

LM 33

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 

1. List some differences between chemical properties of main group elements and sub-group elements.

 

2. Why do some ionic compounds like BaSO₄ have poor solubility in water?
3. How is VSEPR model different from VBT?
4. Explain LCAO.
5. How does the geometry of a molecule influence its stability?
6. Illustrate anti Markownickoff addition of BH₂ during hydroboration.
7. What are silyl amines? How are they prepared?
8. Differentiate metalloboranes and metallocarboranes.
9. Illustrate the contrasting tendency of benzene and borazine toward addition reactions.

 

10. What are cyclic phosphazane? Give the synthesis of one such compound.

 

Part-B

Answer Eight questions. Each question carries five marks 

11. What are the differences in the properties of E-Cl bond in CCl₄ and PbCl₄? Give reasons.

 

12. Give the significance of electronegativity and electronegativity difference citing examples.

 

13. Explain characteristic reactions of (i) electron-rich and (ii) electron-deficient molecules.

 

14. Give a brief account of interhalogen compounds.

 

15. Why does Xe alone form compounds among noble gases? Why does it combine only with some halogens and oxygen?

 

16. Why is SO₂ a good oxidizing agent while SeO₂ and TeO₂ are not?

 

17. Give an account of the synthesis and structural aspects of isopoly molybdates and tungstates.

 

18. Explain the method of synthesizing two-cage phosphorous sulfides.

 

 

 

 

 

19. What are cyclic metaphosphates? Give an account of their synthesis and structural aspects.

 

20. Write a note on linear polyphosphazenes.

 

21. Explain the utility of organochlorides of nonmetals for catenation by coupling.

 

22. Cite an account of the synthesis of two homocyclic inorganic rings.

 

Part-C

Answer Four  questions. Each question carries ten marks 

23. 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.

 

24. Discuss the unique chemical properties of boron and nitrogen group elements and their compounds.

 

25. Discuss allotropes of carbon and their properties.

 

26. Explain the solvolysis reactions of nonmetal halides and organohydrides.

 

27. Give a brief account of the preparation of polyhedral borane anions. Explain the structure and bonding in these compounds with the help of PSEPT.

 

28. (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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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

GH 3

SECOND SEMESTER – APRIL 2008

CH 2809 – CHEMISTRY OF MAIN GROUP ELEMENTS

 

 

 

Date : 22/04/2008            Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

PART-A

Answer all questions. Each question carries two marks 

1. Differentiate catenation and heterocatenation. The tendency of catenation of Group14 elements decreases from carbon through lead. Comment.
2. Draw the structure of [Si₆O₁₈]^12-.
3. What are torands? Cite an example.
4. Give the structure of corrphycene.
5. What are alumazenes?
6. What are pyrazolylborates? Give an example.
7. The inorganic analogue of benzene is different from the latter in its reactivity. Rationalize.
8. What are metalloboranes?
9. Give the structure of tetrasulfur tetranitride.
10. Depict the structure of cyclotrisilane. Comment upon its photochemical cleavage.

PART-B

Answer eight questions. Each question carries five marks 

11. Give an account of the complexes of alkali metals with crown ethers.
12. Explain the biological roles of ionophores.
13. Give an account of the synthesis of polyhedral borane anions.
14. Explain the synthesis of macrocyclic amines and imines.
15. Explain the structure of pyroxenes. How are they related to amphiboles?
16. Write a note on boron-nitrogen clusters.
17. Give an account of the structure and coordination property of mono- and diphosphine ligands.
18. Write a note on aminophosphanes.
19. Explain the solvolysis reaction involving the halides and organohydrides of boron and aluminium.
20. Explain the methods of synthesizing chlorine fluorides.
21. Give a brief account of the synthesis and application of boron nitrides.
22. Explain a high energy experimental technique used to synthesize inorganic compounds.

PART-C

Answer four questions. Each question carries ten marks 

23a. Differentiate harsh and moderate fluorinating agents of main group elements. Cite examples of each class.

1. Explain the synthetic utility of these fluorinating agents.

24a.  What are isopoly and heteropoly acids?

1. Give an account of the synthesis and structure of  iso- and heteropolymolybdates and tungstates.

25a. What are carboranes? Explain the synthesis of ortho-carborane.

1. Explain the synthesis, structural features, and polyhedral rearrangement of carboranes.
2. Explain the methods of synthesizing fluorides and chlorides of boron, phosphorus, and nitrogen.
3. Explain the complexes of alkali metals with -diketones, crown ethers, and calixarenes.

28a. Explain the structural features of zeolites.

1. Highlight the difference between natural and synthetic zeolites.

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WD 32

     LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

SECOND SEMESTER – April 2009

CH 2815/CH 2809 – CHEMISTRY OF MAIN GROUP ELEMENTS

 

 

 

Date & Time: 22/04/2009 / 1:00 – 4:00         Dept. No.                                                           Max. : 100 Marks

 

 

PART – A

 

Answer ALL the questions                                                                                     (10 x 2 = 20)

 

1. What are electron deficient compounds? Give an example.
2. Why are oxides of non-metals acidic?
3. What are calixeranes?
4. Give the structure and laboratory use of iodinepentoxide.
5. How is inorganic benzene prepared?
6. What is the reaction of an alcohol with disilaethenes?
7. What are pyrazoboles? Give two examples.
8. Mention any two applications of sulphides of phosphorus.
9. How is C₂B₁₀H₁₂, carboranes prepared? Give the structure
10. Which of the following compounds possesses high Lewis basicity.
11. i) Si(CH₃)₄  ii) As(CH₃)₄. Give reasons.

 

PART – B

Answer any EIGHT  questions                                                                               (8 x 5 = 40)

 

11. Compare the catenation properties of carbon and silicon, assigning reasons.
12. Explain the biological significance of magnesium.
13. Compare structures and properties of allotropes of carbon.
14. Give preparation, properties and structures of any two chlorine oxides.
15. Give preparation of oxides of xenon. Why are they not obtained by direct combination?
16. Write notes on synthetic importance of boranes.
17. Explain the principle and the role of brominating mixture (bromate-bromide) in volumetric analysis
18. Explain the different methods (any four) of preparation of lithium organometallic compounds.
19. Explain the classification of silicates with examples.
20. Discuss the preparation, properties and uses of silanes.
21. Discuss the synthetic applications of any two sulphides of phosphorus and discuss their structures.
22. What are macrocyclic ligands ? Give the molecular structure of any two nitrogen containing macrocyclic ligands and explain their significances.

 

PART – C

 

Answer any FOUR questions                                                                                  (4 x 10 = 40)

 

23. Discuss nature of bonds present in E-H and E-X and their reactivity.

(E= carbon and silicon; X= halogen)

24. Discuss the preparation, structure and chemistry of various halogen compounds of nitrogen.
25. Write an essay on organometallic compounds with reference to their stabilities and synthetic significance.
26. Explain Why borazine is considered as inorganic benzene where as phosphazenes are not considered as inorganic benzene?
27. Explain the structure and bonding in diborane.
28. Discuss the types of bonding by giving styx number and predict the geometry of the following compounds by PSEPT theory
29. i) B₅H₁₁  ii)B₅H₉           iii)B₄H₁₀          iv) B₆H₁₀

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

SECOND SEMESTER – APRIL 2012

CH 2815 / 2809 – CHEMISTRY OF MAIN GROUP ELEMENTS

 

 

Date : 19-04-2012             Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

          Part – A

Answer all the questions:                                                                                                        (10 x 2 = 20)

1. What is oxidative addition of hydrogen? Give an example.
2. What are fullerenes? Mention any one application.
3. Differentiate the structure of graphite and diamond.
4. What is hetero catenation? Mention any one significance.
5. What is molybdenum blue?
6. Give the structure of porphyrin metal complexes where it act as a tridentate ligand.
7. How does the Tolman cone angle define the steric requirements of a phosphine ligand?
8. Draw the structure of beryllocene and compare it with ferrocene.
9. Why can’t the cis isomer of difluorodiazene be stored in glass vessels?
10. Name the products formed by the disproportionation of xenon trioxide in basic solution.

Part – B

Answer any eight questions:                                                                                                    (8 x 5 = 40)

11. Write a brief note on hydroboration and hydrosilaylation. Give mechanisms also.
12. How is it possible to convert closoborane to nido and arachnoboranes? Explain by taking B₆H₆^12- as an example.
13. Explain PSEPT theory and apply it to predict the structure of
14. i) 1,2-CpCoB₄H₈ ii)NB₉H₁₂
15. Explain the classification of silicates. Give an example for each class.
16. Write a brief note on tungsten bronze.
17. Explain why borazines are considered as inorganic benzene where as phosphazenes are not considered as inorganic benzene.
18. What are pthalocyanins? How are they prepared? Mention their uses.
19. Mention a method to synthesis alkyl and aryl silicon halides and explain their hydrolysis reaction to give various polymers.
20. Explain macrocyclic effect with suitable examples.
21. An inorganic sulphur halide ‘A’ having a distinct sulphurodour is made by the reaction between SCl₂ and HF in the presence of pyridine to give compound ‘B’. The compound B has an octahedral geometry. Compound ‘A’ can also react with ClF to give compound ‘C’. Compound ‘C’ on reaction with ozone gives peroxide ‘D’. Identify A, B, C and D and write the equations for the above reactions.
22. Give a brief account on the chemistry of oxohalogen fluorides.
23. Write the preparation of chloramine and compare its disinfectant property with chlorine.

Part – C

Answer any four questions                                                                                                      (4 x 10 = 40)

23. Compare the reactivity of electron deficient, electron precise and electron rich compounds of main group elements.
24. Discuss the structure, bonding and chemical reactivity of diborane.
25. Derive styx number and possible structure for B₄H
26. a) Write a brief note on naturally occurring azamacrocycles.                                             (6)
27. b) Write a note on polypyrazolyl borate (4)
28. a) An inorganic halogen oxide ‘A’ which is used as an air disinfectant is paramagnetic at room temperature and diamagnetic at -150ºC. Identify A and give reason for its different   magnetic character by giving its structure.                                                                                         (5)
29. b) Discuss the nature of metal-phosphorous bond in phosphine ligand.                           (5)
30. a)Explain the classification of non-metal fluorides as fluorinating agents with suitable                                                                                                                               (5)
31. b) Mention the synthetic applications of organolithium compounds. (5)

 

 

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