SECTION-A (NEXT FOURTY FIVE QUESTIONS: SINGLE CHOICE ONLY ONE CORRECT ANSWER) (c) (c.) (c.) (b.) Dimerization of benzoic acid

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1 th Mains 7 th Aug Chemistry Paper Solution Subject-EMISTRY Part : SECTIN-A (NEXT FURTY FIVE QUESTINS: SINGLE ICE NLY NE CRRECT ANSWER) Q Q A compound formed by elements A and B crystallizes in cubic structure where A atoms are at the corners of a cube and B atoms are at the face centre. The formula of the compound is: AB AB The mass of a unit cell of CsCl corresponds to: AB 4 None of these 8 Cs and Cl Cs and 6 Cl Cs and Cl 4 Cs and 4 Cl Q If spheres of radius Q4 consecutive A layer is: 4r Because a 'r' are arranged in a ccp fashion (ABCABC ), the vertical distance between any two 4r 4r a 4r 6 r The molecular mass of benzoic acid in benzene as determined by depression in freezing point method corresponds to: Ionization of benzoic acid Trimerization of benzoic acid Dimerization of benzoic acid Salvation of benzoic acid Q5 Solute A is a ternary electrolyte and solute B is non-electrolyte. If 0. M solution of solute B produces an osmotic pressure of P, then equal to: 0.05 M solution of A at the same temperature will produce an osmotic pressure P.5 P P P r 6 (d) For ternary electrolyte; P CST 0.05 S T 0, Blue Diamond Complex, Fatehgunj, Vadodara-0.Tel. No / / 78

2 th Mains 7 th Aug Chemistry Paper Solution For B ; P 0. S T P P Q6 Insulin (C H05 ) n is dissolved in a suitable solvent and the osmotic pressure ( ) of solutions of various concentrations (g /cm ) C is measured at 0 C. The slope of a plot of against C is found to be The molecular mass of the insulin is : (d) Q7 A beaker containing 0 g sugar in 00 g water and another containing 0 g sugar in 00 g water are placed under a bell-jar and allowed to stand until equilibrium is reached. The amount of water which will be transferred from one beaker to other is :.0 g 0 g. g 66.7 g At equilibrium both the solutions have same V.P. as well as same concentrations because both the solutes are non-electrolyte. Suppose w g water is transferred from dilute solution to concentrated solution, then and, Volume of solvent volume of solution (for dilute solutions) Q8 faraday of electricity are passed through molten Al, aqueous solution of CuS 4 and molten NaCl taken in three different electrolytic cells. The amount of the ratio of: mole : mole : mole Al, Cu and Na deposited at the cathodes will be in mole : mole : mole 0, Blue Diamond Complex, Fatehgunj, Vadodara-0.Tel. No / / 78

3 th Mains 7 th Aug Chemistry Paper Solution 4 mole :. 5 mole : mole. 5 mole : mole : mole Q9 Value of E may be calculated from E E E E E E Let the corresponding free energies are G, G and, G then E E Q0 For the cell reaction; Cu Zn Zn Cu, (C aq) (s) (C aq) the change in free energy (Δ G) at a given temperature is a function of: ln C ln (C /C) (s) ln (C C ) Q How much will the reduction potential of a hydrogen electrode change when its solution initially at ph 0 is neutralized to ph 7? Increase by V Decrease by V Increase by 0.4 V Decrease by 0.4 V ln C (d) Q An endothermic reaction A B have an activation energy 5 kcal/mol and the heat of the reaction is 5 kcal/mol. The activation energy of the reaction B A is: 0 kcal/mol 5 kcal/mol 0 kcal/mol Zero Q For A B C D, Δ H 0 kj mol, the activation energy of the forward reaction is 85 kj mol. The activation energy for backward reaction is. kj mol For a reaction 85 A 0 E a for forward reaction = E a for backward reaction H or A 05 kj mol 0, Blue Diamond Complex, Fatehgunj, Vadodara-0.Tel. No / / 78

4 th Mains 7 th Aug Chemistry Paper Solution 5 Q4 The rate constant, the activation energy and the Arrhenius parameter of a chemical reaction at.0 0 s 4, 04.4 kj mol and s respectively. The value of the rate constant as s s Infinity s 5 C are T is: K Ae E a / RT E / RT At T, e a or K A sec Q5 Consider the following statements :. increase in concentration of reactant increase the rate of zero order reaction. Rate constant K is equal to collision frequency A if E 0. Rate constant K is equal to collision frequency A if E 0 4. ln K vs. T is a straight line 5. ln K vs. / T is a straight line Correct statement are : and 4 and 5, 4 and 5, and 5 a a Rate of zero order reaction is independent of concentration when E a 0, K A and, K A ln K E a vs. / T is straight line. Q6 Match the following Reactants Products (A) H Cl, moist Ag (i) N C 5 (B) C 5 H Cl, aqueous ethanolic AgCN (ii) C H 4 (C) (D) C 5 H Cl, aqueous ethanolic AgN (iii) C 5 H Cl, ethanolic K (iv) NC (v) C H 6 The correct match is (A)-(v), (B)-(iii), (C)-(iv), (D)-(i) (A)-(iii), (B)-(iv), (C)-(i), (D)-(ii) moist Ag 5Cl aq. C H Cl ethanolic 5 AgCN NC (A)-(i), (B)-(ii), (C)-(iii), (D)-(iv) (A)-(iv), (B)-(i), (C)-(ii), (D)-(v) 0, Blue Diamond Complex, Fatehgunj, Vadodara-0.Tel. No / / 78

5 th Mains 7 th Aug Chemistry Paper Solution 6 aq. ethanoilc C H5Cl N C AgN ethanolic H5Cl K Q7 Ethyl alcohol is used as a preservative for chloroform because it prevents aerial oxidation of chloroform decomposes phosgene to C and Cl prevents decomposition of chloroform removes phosgene by converting it to ethyl carbonate (d) Phosgene is poisonous gas, ethyl alcohol converts phosgene into ethyl carbonate Q8 In the reaction sequence Compound ' X' is Chlorobenzene Benzene Toluene Biphenylmethane Cl FeCl CCl - H S 4 final product (DDT) Q9 Arrange the given compounds in order of increasing boiling point. (I) (II) (III) (IV) IV > III > II > I IV > III > I > II III > IV > I > II III > IV > II > I Extent of H-bonding is more in diol than alcohol. Q0 Which of the following compounds fail to give a carbonyl compound when it is passed over red hot copper at 57 K? C C 0, Blue Diamond Complex, Fatehgunj, Vadodara-0.Tel. No / / 78

6 th Mains 7 th Aug Chemistry Paper Solution 7 Cu HC C C H 57K HC C C Q When glycerol is heated with a few crystals of KHS 4, a foul smelling gas is evolved. The gas evolved is methyl isocyanide C Acrolein phosgene -- KHS 4 (dehydrating agent) -- H C- - H C- -C-H H C- - =- Q -Phenylethanol can be prepared by the reaction of benzaldehyde with iodomethane, Mg, ether followed by hydrolysis iodomethane, AlCl followed by hydrolysis conc. Na, Cannizzaro s reaction iodoethane, Mg, ether, H Mg PhCH I ether MgI Ph Q Ethyl acetate is obtained when methyl magnesium iodide reacts with ethyl formate ethyl chloroformate acetyl chloride Carbon dioxide Cl C ε t MgI H C C ε t Q4 Which of the following reduces Fehling s solution? Formic acid Benzaldehyde Acetone None of these H C C Fehling Solution R'C R C Q5 Which of the following reagents can convert ketones into esters? Per acid Carboxylic acid Alcohol Lewis acid R C 0, Blue Diamond Complex, Fatehgunj, Vadodara-0.Tel. No / / 78

7 th Mains 7 th Aug Chemistry Paper Solution 8 Q6 H /H + A. The compound (A) is H /H + + H H -H Q7 Glycerol [] HCN KCN(alc) H /H HCl X Y Z B A ' B' is Citric acid Ascorbic acid Tartaric acid Saccharic acid Q8 Citric acid is Br CC C HC HC C C H 5 Zn C H/H A B C The compound ' C' is Br Cε t Zn H HC C Cε t C C BrZn Cε t ZnBr Cε t Q9 The product(s) obtained via oxymercuration (HgS4 H S 4 ) of -butyne would be C H C HC 0, Blue Diamond Complex, Fatehgunj, Vadodara-0.Tel. No / / 78

8 th Mains 7 th Aug Chemistry Paper Solution 9 Q0 MDM C C H N N The above reaction occurs at ph 4.5 ph ph Any value of ph Reaction occurs at moderate ph. 0, Blue Diamond Complex, Fatehgunj, Vadodara-0.Tel. No / / 78

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