Chemistry Ii

CHEMISTRY-II TIME ALLOWED: 3 HOURS MAXIMUM MARKS: 100 Note: Attempt FIVE questions in all, including QUESTION NUMBER 8 which is, COMPULSORY. All questions carry equal marks. 1. (a) What is enzyme catalysis? Derive the expression for the mechanism of enzyme catalysed reaction. (12) (b) Discuss salient features of the LCAO theory giving at least two examples. (8) 2. (a) Prove the cyclic structure of glucose and give its important properties. (6+6) (b) How will you bring about the following transformations: (8) (i) Aldohexose into Aldopentose (ii) Aldopentose into Aldohexose 3. Write comprehensive notes of any TWO of the following: (10+10) (i) Hydrogen bonding (ii) Polymerization (iii) Stereoisomerism 4. (a) Explain the structure of Benzene in terms of Molecular Orbital Theory.(8) (b) How does the presence of the following groups effect the orientation and reactivity of benzene in di-substitution reactions: (i) Alkyl group (ii) Halogen atom (iii) Nitro group.(12) 5. Explain in detail, the following terms giving suitable examples: (4 each) (1) Lyate ion (ii) Molecularity (iii) Diazotisation (iv) Mutarotation (v) Solvolysis. 6. Explain why? (4 each) (i) Aryl diazonium cation is stable at 00C while alkyl diazonium cation is not. (ii) B. pt of p-hydroxy benzoic acid is higher than that of the 0—isomer. iii.Dipole moment of C is - 1,2— dichloroethene is zero while that of the terns isomer is not zero (iv) Dry ether is used as a solvent in the synthetic reactions of Grignards reagent. (v) Benzyl chloride forms precipate with a solution of silver nitrate while Phenyl chloride does not. 7. (a) Derive the" K= Ae—E,, (10) RT (b) Discuss the significance of "A" and "E" in the above rate equation. (10) COMPULSORY QUESTION 8. (a) Fill in the blanks with appropriate terms. (20) (1) Forces responsible for holding individual layers in layer structured solids are called ----------

(2) Boron halides have a ---------- shape according to VESPER theory. (3) DNA consists of a double helix, the two strands of the helix are held together by------(4) Aromatic diazonium cations undergo ------------ substitution reactions. (5) ----- is used as a-catalyst in friedle craft acylation reaction. (6) Reaction of 2— bromobutane with Sodium ethoxide using acetone as a solvent proceeds by ---------mechanism. (7) Boat conformation of cyclohexane is less stable than the chair conformation because of-------------. (b) Correct the following statements, if necessary: (8) Organo cadmium compounds are also called Grignards reagent. (9) A catalyst can alter the equilibrium constant of a reaction. (10) A secondary amine is more basic than a primary amine. (11) Acetone can be reduced to propane by reduction with LiA1H4. (12) The H-C-C angle in ethyne is 120 ° . (13) Bond order of He2 molecule is zero. (14) Saponification of an ester is an example of first order reaction. (c) Choose the correct answers: (15) The geometry of d2sp3 by bridized orbitals is: (a) Trigonal (b) tetrahedral (c) pyrimidal (d) angular (e) None of these. (16) Hydrogen molecule, is: (a) Paramagnetic (b) Diamagnetic (c) Ferromagnetic (d) None of these. (17) Reactions catalysed by enzymes are: (a) 1st order (b) 2nd order (c) 3rd order (d) Zero order (e) None of these. (18) According to VESPER theory, shape of PCI5 molecule is: (a) Trigonal planer (b) tetra hedral (c) trigonal bipyrimidal (d) octahedral (e) None of these.

(19) An example of a layer structured solid is (a) Napthalene (b) Sodium Cholride (c) Diamond. (d) Cadmium iodide. (e) None-of these. (20) Halogenation of alkanes in the presence of diffused sunlight is carried out in the solvent: (a) Acetone (b) Diethylether (c) Water (d) Dimethyl formamide (e) None of these. **********************************