This document contains an unsolved chemistry exam from 1995 containing 50 multiple choice questions testing concepts related to general chemistry, organic chemistry, and physical chemistry. The questions cover topics such as buffers in blood, protein structure, ATP generation from glucose, enzyme properties, organic reactions, acid-base properties, radioactivity, gas laws, and thermodynamics.

1. aipmt–Past papersCHEMISTRY- UNSOLVED PAPER - 1995

2. SECTION – I (Total Marks : 50)Single Correct Answer TypeThere are five parts in this question. Four choices are given for each part and one of them is correct. Indicate you choice of the correct answer for each part in your answer-book by writing the letter (a), (b), (c) or (d) whichever is appropriate.

3. 01ProblemThe pH value of blood does not appreciably change by a small addition of an acid or a base, because the blood Can be easily coagulated Contains iron as a part of the molecule Is a body fluidContains serum protein which acts as buffer.

4. Problem02The secondary structure of a protein refers to Regular folding patterns of contiguous portions of the polypeptide chain Three-dimensional structure, specially the bond between amino acid residues that are distant from each other in the polypeptide chain Mainly denatured proteins and structures of prosthetic groupLiner sequence of amino acid residues in the polypeptide chain.

5. Problem03The oxidation of glucose is one of the most important reactions in a living cell. What is the number of ATP molecules generated in cells from one molecule of glucose? 28381218.

6. Problem04Which of the following statements about enzymes are true? Enzyme catalyse chemical reactions by lowering the activation energy Enzymes are highly specific both in binding chiral substrates and in catalyzing their reactions Enzymes lack in nucleophilic groupsPepsin is proteolytic enzyme.

7. Problem05The bakelite is prepared by the reaction between Phenol and formaldehyde Tetramehtylene glycol Urea and formaldehydeEthylene glycol.

8. Problem06Which product is formed, when acetonitrile is hydrolysed partially with cold concentrated HCl? Methyl cyanideAcetic anhydridesAcetic acidAcetamide.

9. Problem07Which one of the following products is formed when adipic acid is heated?a. b. c. d.

10. Problem08The most suitable method of the separation of a 1 : 1 mixture of ortho-and para-nitrophenols is Crystallization Chromatography Distillation Sublimation.

11. Problem09The order reactivity of carbonyl compounds for nucleophilic addition is H2C=O > R2C=O > Ar2C=O > RCHO >.H2C=O > RCHO > ArCHO > R2C=O >Ar2C=OArCHO > Ar2C = O > RCHO > R2C = O > H2C = O

12. Problem10In the reaction CH3CHO + HCN -> CH3CH(OH)CN, a chiral center is produced. This product is Dextrorotatory Racemic mixture Meso compoundLaevorotatory .

13. Problem11The oxidation of toluene with CrO3 in the presence of (CH3CO)2O gives a product A, which on treatment with aqueous NaOH, produces C6H5COONa2,4-diacetyl tolueneC6H5CHO(C6H5CO)2O.

14. Problem12When 3, 3-dimethyl 2-butanol is heated with H2SO4, the major product obtained is 2, 3-dimethyl 2-butene cids and trans isomers of 2,3-dimethyl 2-butene2, 3-dimethyl 1-butene3,3-dimethy 1-butene.

15. Problem13The alkene R-CH=CH2 reacts readily with B2H6 and the product on oxidation with alkaline hydrogen peroxides produces a.b.c. R-CH2-CHOd. R-CH2-CH2-OH.

16. Problem14When aniline reacts with oil of bitter almonds (C6H5CHO) condensation takes place and benzal derivative is formed. This is known as Schiff’s baseBenedict’s reagent Million’s baseSchiff’s reagent.

17. Problem15In which of the following compound there is more than one kind of hybridization (sp, sp2, sp3) for carbon? CH2=CH-CH=CH2H-C C-HCH3CH2CH2CH3CH3-CH=CH-CH3.

18. Problem16The IUPAC name for CH3CH=CHCH2CHCH2COOH is3-amino 5-heptenoic acidβ-amino ρ-heptenoic acid 5-amino 2-heptenoic acid5-amino hex-2-ene-carboxylic acid.

19. Problem17Amongst TiF62-,CoF63-,Cu2Cl2 and NiCl42-, which are the colourless species? (atomic number of Ti = 22, Co = 27, Cu = 29, Ni = 28) CoF63-and NiCl42-TiF62-and Cu2Cl2Cu2Cl2 and NiCl42-TiF62- and CoF63-

20. Problem18The coordination number and oxidation state number of Cr in K3Cr(C2O4)3 are respectively 3 and + 33and 06 and + 34 and + 2.

21. Problem19The number of geometrical isomers for [Pt(Nh3)2Cl2], is 3142

22. Problem20In metal carbonyl having general formula M(CO)x where M = meral, x = 4 and the metal is bonded to Carbon and oxygen C O tripe bond Oxygen Carbon.

23. Problem21The mercury is the only metal which is liquid at 00C. This is due to its High vapor pressure Weak metallic bond High ionization energy Both (b) and (c).

24. Problem22Aluminum (III) chloride forms a dimmer because aluminum Belongs to 3rd groupCan have higher coordination number Cannot form a trimmer Has high ionization energy.

25. Problem23The solubility in water of sulphate down the Be group is Be > Mg > Ca > Sr > Ba. This is due to Decreasing lattice energy High heat of salvation for smaller ions like Be2+Increases in melting points Increasing molecular weight.

26. Problem24The sodium is made by the electrolysis of a molten mixture of about 40% NaCl and 60% CaCl2 becauseCa++ can displace Na from NaClThis mixture has a lower melting point than NaClCaCl2 helps in conduction of electricity Ca++ can reduce NaCl to Na.

27. Problem25On heating one end of a place of metal, the other end becomes hot because of Energized electrons moving to the other end Minor perturbation in the energy of atoms Resistance of the metal Mobility of atoms in the metal.

28. Problem26Identify the correct statement Plaster of Paris can be obtained by hydration of gypsum Plaster of Paris is obtained by partial oxidation of gypsumGypsum contains a lower percentage of calcium than plaster of Paris Gypsum is obtained by heating plaster of Paris.

29. Problem27The BCl3 is a planar molecule whereas NCl3 is pyramidal because Nitrogen atom is smaller than boron atom BCl3 has no lone pair but NCl3 has a lone pair of electrons B-Cl bond is more polar than N-CI bondN-Cl bond is more covalent than B-Cl bond

30. Problem28About 20 Km above the earth, there is an ozone layer. Which one of the following statements about ozone and ozone layer is true? It is beneficial to us as it stops U.V. radiation Conversion of O3 to O2 is an endothermic Ozone has a triatiomic linear molecule It is harmful as it stops useful radiation.

31. Problem29According to Raoult’ s law, the relative lowering of vapor pressure for a solution is equal to Mole fraction of solute Mole fraction of solvent Moles of solute Mole of solvent.

32. Problem30The oxide, which cannot act as a reducing agent, is CO2ClO2NO2SO2.

33. Problem31Half-life for radioactive 14C is 5760 years. In how many years 200 mg of14C will be reduced to 25 mg ? 17280 years23040 years5760 years11520 years.

34. Problem32If enthalpies of formation for C2H4(g), CO2(g) and H2O (l) at 250C and 1 atom pressure are 52, -394 and –286 kJ/mol respectively , then enthalpy of combustion of C2H4(g) will be + 14.2 kJ/mol+ 1412 kJ/mol-141.2 kJ/mol-1412 kJ/mol

35. Problem33An electrochemical cell is set up as : Pt; H2 (1 atm)|HCl(0.1 M)|| CH3COOH (0.1M) |H2 (1 atm); Pt, The e.m.f. of this cell will not be zero, because Acids used in two compartments are different e.m.f. depends on molarities of acids used The temperature is constant pH of 0.1 M HCl & 0.1 M CH3COOH is not same

36. Problem34 The pH value of a 10 M solution of HCl is Equal to 1Equal to 2Less than 0Equal to 0.

37. Problem35A chemical reaction is catalyzed by a catalyst X . Hence X Reduces enthalpy of the reactionDoes not affect equilibrium constant of reaction Decreases rate constant of the reactionIncreases activation energy of the reaction

38. Problem36An ideal gas, obeying kinetic energy theory of gases can not be liquefied, because It solidifies before becoming a liquidForces acting between its molecules are negligible Its critical temperature is above 00CIts molecules are relatively small in size .

39. Problem37Standard state Gibb’s free energy change for is omerizxation reaction cis-2-pentene trans-2-pentene is –3.67 kJ/mol at 400 K. If more trans-2-pentene is added to the reaction vessel, then Equilibrium remains unaffected Equilibrium is shifted in the forward direction More cis-2-pentene is formed Additional cis-2-pentene is formed .

40. Problem38For a reaction to occur spontaneously H must be negative S must be negative ( H - T S) must be negative ( H + T S) must be negative.

41. Problem39The solubility of AgCl will be minimum in0.01 M CaCl2Pure water 0.001AgNO30.01M NaCl

42. Problem40The concentration units, independent of temperature, would be Normality Weight volume percent MolalityMolarity.

43. Problem41The dimensions of pressure are the same as that ofForce per unit volume Energy per unit volume Force Energy.

44. Problem42In liquid- gas equilibrium, the pressure of vapours above the liquid is constant at Constant temperature Low temperature High temperature None of these

45. Problem43The number of moles of oxygen in one liter of air containing 21% oxygen by volume, under standard conditions , is 0.0093 mole2.10 moles 0.186 mole0.21 mole.

46. Problem44Uncertainty in position of an electron an electron (mass = 9.1 x 10-28 g) moving with a velocity of 3 x 104 cm/s accurate up to 0.001% will be (Use h/( ) in uncertainly expression where h = 6.626 x 10-27 erg-second) 5.76 cm7.68 cm1.93 cm3.84 cm.

47. Problem45Which of the following species is paramagnetic ?CO2CN-O22-NO.

48. Problem46The radius of hydrogen atom in the ground state is 0.53 Ǻ . The radius of Li2+ ion (atomic number = 3 ) in a similar state is 0.53 Ǻ1.06 Ǻ0.17 Ǻ0.265 Ǻ.

49. Problem47The correct order of the O-O bond length in O2, H2O2 and O3 is O2 > H2O2 > O3H2O2 > O3 > O2O2 > O3 > H2O2O3 > H2O2 > O2 .

50. Problem48The electronic configuration of an element is 1s2 2s2 2p23s23p2. What is the atomic number of the element , which is just below the above element in the periodic table ? 36493334.

51. Problem49After the emission of one α-particle followed by one β-particle from the atom of x92282 the number of neutrons in the atom will be 144143148146.

52. Problem50The ground state electronic configuration of valence shell electrons in the nitrogen molecule (N2) is written as .Hence the bond order in nitrogen molecule is 2301.

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