AIPMT Chemistry 1995

aipmt–Past papers: 

aipmt–Past papers CHEMISTRY- UNSOLVED PAPER - 1995

SECTION – I (Total Marks : 50): 

SECTION – I (Total Marks : 50) Single Correct Answer Type There 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 .

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01 The 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 fluid Contains serum protein which acts as buffer. Problem

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Problem 02 The 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 group Liner sequence of amino acid residues in the polypeptide chain.

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Problem 03 The 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? 28 38 12 18.

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Problem 04 Which 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 groups Pepsin is proteolytic enzyme.

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Problem 05 The bakelite is prepared by the reaction between Phenol and formaldehyde Tetramehtylene glycol Urea and formaldehyde Ethylene glycol.

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Problem 06 Which product is formed, when acetonitrile is hydrolysed partially with cold concentrated HCl ? Methyl cyanide Acetic anhydrides Acetic acid Acetamide .

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Problem 07 Which one of the following products is formed when adipic acid is heated? a. b. c. d.

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Problem 08 The most suitable method of the separation of a 1 : 1 mixture of ortho -and para-nitrophenols is Crystallization Chromatography Distillation Sublimation.

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Problem 09 The order reactivity of carbonyl compounds for nucleophilic addition is H 2 C=O > R 2 C=O > Ar 2 C=O > RCHO > . H 2 C=O > RCHO > ArCHO > R 2 C=O >Ar 2 C=O ArCHO > Ar 2 C = O > RCHO > R 2 C = O > H 2 C = O

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Problem 10 In the reaction CH 3 CHO + HCN → CH 3 CH(OH)CN, a chiral center is produced. This product is Dextrorotatory Racemic mixture Meso compound Laevorotatory .

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Problem 11 The oxidation of toluene with CrO 3 in the presence of (CH 3 CO) 2 O gives a product A, which on treatment with aqueous NaOH , produces C6H5COONa 2,4-diacetyl toluene C6H5CHO (C 6 H 5 CO) 2 O.

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Problem 12 When 3, 3-dimethyl 2-butanol is heated with H 2 SO 4 , the major product obtained is 2, 3-dimethyl 2-butene cids and trans isomers of 2,3-dimethyl 2-butene 2, 3-dimethyl 1-butene 3,3-dimethy 1-butene.

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Problem 13 The alkene R-CH=CH 2 reacts readily with B2H6 and the product on oxidation with alkaline hydrogen peroxides produces a. b. c. R-CH 2 -CHO d. R-CH 2 -CH 2 -OH.

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Problem 14 When aniline reacts with oil of bitter almonds (C 6 H 5 CHO) condensation takes place and benzal derivative is formed. This is known as Schiff’s base Benedict’s reagent Million’s base Schiff’s reagent.

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Problem 15 In which of the following compound there is more than one kind of hybridization (sp, sp 2 , sp 3 ) for carbon? CH 2 =CH-CH=CH 2 H-C C-H CH 3 CH 2 CH 2 CH 3 CH 3 -CH=CH-CH 3 .

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Problem 16 The IUPAC name for CH 3 CH=CHCH 2 CHCH 2 COOH is 3-amino 5-heptenoic acid β-amino ρ- heptenoic acid 5-amino 2-heptenoic acid 5-amino hex-2-ene-carboxylic acid.

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Problem 17 Amongst TiF 6 2- ,CoF 6 3- ,Cu 2 Cl 2 and NiCl 4 2- , which are the colourless species? (atomic number of Ti = 22, Co = 27, Cu = 29, Ni = 28) CoF 6 3- and NiCl 4 2- TiF 6 2- and Cu 2 Cl 2 Cu 2 Cl 2 and NiCl 4 2- TiF 6 2- and CoF 6 3-

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Problem 18 The coordination number and oxidation state number of Cr in K 3 Cr(C 2 O 4 ) 3 are respectively 3 and + 3 3and 0 6 and + 3 4 and + 2.

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Problem 19 The number of geometrical isomers for [Pt(Nh 3 ) 2 Cl 2 ], is 3 1 4 2

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Problem 20 In 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.

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Problem 21 The mercury is the only metal which is liquid at 0 0 C. This is due to its High vapor pressure Weak metallic bond High ionization energy Both (b) and (c).

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Problem 22 Aluminum (III) chloride forms a dimmer because aluminum Belongs to 3 rd group Can have higher coordination number Cannot form a trimmer Has high ionization energy.

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Problem 23 The 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 Be 2+ Increases in melting points Increasing molecular weight.

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Problem 24 The sodium is made by the electrolysis of a molten mixture of about 40% NaCl and 60% CaCl 2 because Ca ++ can displace Na from NaCl This mixture has a lower melting point than NaCl CaCl 2 helps in conduction of electricity Ca ++ can reduce NaCl to Na.

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Problem 25 On 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.

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Problem 26 Identify the correct statement Plaster of Paris can be obtained by hydration of gypsum Plaster of Paris is obtained by partial oxidation of gypsum Gypsum contains a lower percentage of calcium than plaster of Paris Gypsum is obtained by heating plaster of Paris.

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Problem 27 The BCl 3 is a planar molecule whereas NCl 3 is pyramidal because Nitrogen atom is smaller than boron atom BCl 3 has no lone pair but NCl3 has a lone pair of electrons B- Cl bond is more polar than N-CI bond N- Cl bond is more covalent than B- Cl bond

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Problem 28 About 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 O 3 to O 2 is an endothermic Ozone has a triatiomic linear molecule It is harmful as it stops useful radiation.

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Problem 29 According 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.

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Problem 30 The oxide, which cannot act as a reducing agent, is CO 2 ClO 2 NO 2 SO 2 .

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Problem 31 Half-life for radioactive 14 C is 5760 years. In how many years 200 mg of 14 C will be reduced to 25 mg ? 17280 years 23040 years 5760 years 11520 years.

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Problem 32 If enthalpies of formation for C 2 H 4 (g), CO 2 (g) and H 2 O (l) at 250C and 1 atom pressure are 52, -394 and –286 kJ/mol respectively , then enthalpy of combustion of C 2 H 4 (g) will be + 14.2 kJ/mol + 1412 kJ/mol -141.2 kJ/mol -1412 kJ/mol

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Problem 33 An electrochemical cell is set up as : Pt; H 2 (1 atm )| HCl (0.1 M)|| CH3COOH (0.1M) |H 2 (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 CH 3 COOH is not same

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Problem 34 The pH value of a 10 M solution of HCl is Equal to 1 Equal to 2 Less than 0 Equal to 0.

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Problem 35 A chemical reaction is catalyzed by a catalyst X . Hence X Reduces enthalpy of the reaction Does not affect equilibrium constant of reaction Decreases rate constant of the reaction Increases activation energy of the reaction

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Problem 36 An ideal gas, obeying kinetic energy theory of gases can not be liquefied, because It solidifies before becoming a liquid Forces acting between its molecules are negligible Its critical temperature is above 0 0 C Its molecules are relatively small in size .

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Problem 37 Standard 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 .

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Problem 38 For 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.

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Problem 39 The solubility of AgCl will be minimum in 0.01 M CaCl 2 Pure water 0.001AgNO 3 0.01M NaCl

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Problem 40 The concentration units, independent of temperature, would be Normality Weight volume percent Molality Molarity .

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Problem 41 The dimensions of pressure are the same as that of Force per unit volume Energy per unit volume Force Energy.

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Problem 42 In liquid- gas equilibrium, the pressure of vapours above the liquid is constant at Constant temperature Low temperature High temperature None of these

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Problem 43 The number of moles of oxygen in one liter of air containing 21% oxygen by volume, under standard conditions , is 0.0093 mole 2.10 moles 0.186 mole 0.21 mole.

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Problem 44 Uncertainty in position of an electron an electron (mass = 9.1 x 10 -28 g) moving with a velocity of 3 x 10 4 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 cm 7.68 cm 1.93 cm 3.84 cm.

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Problem 45 Which of the following species is paramagnetic ? CO 2 CN - O 2 2- NO.

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Problem 46 The radius of hydrogen atom in the ground state is 0.53 Ǻ . The radius of Li 2+ ion (atomic number = 3 ) in a similar state is 0.53 Ǻ 1.06 Ǻ 0.17 Ǻ 0.265 Ǻ.

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Problem 47 The correct order of the O-O bond length in O 2 , H 2 O 2 and O 3 is O 2 > H 2 O 2 > O 3 H 2 O 2 > O 3 > O 2 O 2 > O 3 > H 2 O 2 O 3 > H 2 O 2 > O 2 .

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Problem 48 The electronic configuration of an element is 1s 2 2s 2 2p 2 3s 2 3p 2 . What is the atomic number of the element , which is just below the above element in the periodic table ? 36 49 33 34.

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Problem 49 After the emission of one α-particle followed by one β-particle from the atom of x 92 282 the number of neutrons in the atom will be 144 143 148 146.

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Problem 50 The ground state electronic configuration of valence shell electrons in the nitrogen molecule (N 2 ) is written as .Hence the bond order in nitrogen molecule is 2 3 0 1.

Slide 53: 

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