AIPMT Chemistry 2007

aipmt–Past papers CHEMISTRY - UNSOLVED PAPER - 2007

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 .

01 Problem Which one of the following on reduction with lithium aluminum hydride yields a secondary amine ? Methyl isocyanide Acetamide Methyl cyanide Nitroethane.

Problem 02 RNA & DNA are chiral molecule, there chirality is due to Chiral base Chiral phosphate ester units D-sugar components L-sugar components

Problem 03 The Langmuir adsorption isotherm is deduced using the assumption The absorption sites are equivalent in there ability to absorb the particle The heat of absorption varies with coverage The absorption molecules interact with each other The absorption take place in multilayers.

Problem 04 A weak acid, HA, has a Ka,, of 1.00 X 10-5. If 0.100 mol of this acid is dissolved in one liter of water, the percentage of acid dissociated at equilibrium is closed to 1.00% 99.9% 0.100% 99.0%

Problem 05 The reaction of hydrogen & iodine monochloride is given as: H2 (g) + 2ICl(g)->2HCl(g) + I2 (g) These reaction is of first order with respect to H2(g) & HCl(g) , following mechanism were proposed. Mechanism A: H2 (g) + 2ICl(g)->2HCl(g) + I2 (g) Mechanism B: H2 (g) + ICl(g)->HCl(g) + HI2 (g); slow HI(g) + ICl(g) ->HCl(g) + I2 (g) ; fast Which of the above mechanism(s) can be consistent with the given information about the reaction? A & B both Neither A nor B A only B only

Problem 06 The efficiency of a fuel cell is given by ΔG/ΔS ΔG/ΔH ΔS/ΔG ΔH/ΔG

Problem 07 Consider the following reactions: (i) H+(aq) +OH-(aq)=H2O(l) ; ΔH=-X1 kJ mol-1 (ii) H2 (g) +1/2O2 (g) =H2O(l) ; ΔH=-X2 kJ mol-1 (iii) CO2 (g) + H2 (g) =CO(g)+ H2O ; ΔH=-X3 kJ mol-1 (iv) C2 H2 (g) +5/2O2 (g) =2CO2 (g) + H2O(l) ; ΔH=+X4 kJ mol-1 Enthalpy formation of H2O(l) is +X3 kJ mol-1 - X4 kJ mol-1 + X1 kJ mol-1 - X2 kJ mol-1

Problem 08 The correct order of increasing thermal stability of K2CO3 , MgCO3 , CaCO3 & BeCO3 is BeCO3 < MgCO3< CaCO3< K2CO3 MgCO3< BeCO3 < CaCO3< K2CO3 K2CO3< MgCO3< CaCO3< BeCO3 BeCO3< MgCO3< K2CO3< CaCO3

Problem 09 In which of the following pairs, the two species are iso-structural ? SO32- & NO3- BF3 & NF3 BrO3- & XeO3 SF4 & XeF4

Problem 10 Which of the following oxidation states are the most characteristic for lead & tin respectively? +2, +4 +4, +4 +2 ,+2 +4, +2

Problem 11 Which of the following statement, about the advantage of roasting of sulphide ore before reduction is not true ? The ΔG0f of the sulphide is greater than those for CS2 & H2S. The ΔG0f is negative for roasting of sulphide ore to oxides Roasting of sulphides to the oxide is thermodynamically feasible. Carbon & hydrogen are suitable reducing agents for metal sulphides

Problem 12 In a first order reaction A->B , if k is rate constant & initial concentration of the reactant A is 0.5 M , then the half life is a. b. c. d.

Problem 13 The correct decreasing order of their reactivity towards hydrolysis is (i) C6H5COCI (ii) (iii) (iv) (i) > (ii) >(iii)> (iv) (iv) >(ii) >(i) > (iii) (ii) > (iv) > (i) > (iii) (ii) > (iv) >(iii) >(i)

Problem 14 Predict the product C obtained in the following reaction of butyne-1. CH3CH2-C≡CH + HCl a. b. c. d.

Problem 15 Concentrated aqueous sulphuric acid is 98% H2SO4 by mass & has a density of 1.80 g mL-1. Volume of acid require to make one liter of 0.1M H2SO4 solution is 16.65 mL 22.20 mL 5.55 mL 11.10 mL

Problem 16 Reduction of aldehydes & ketones into hydrocarbons using zinc amalgam & con.HCl is called Cope reduction Dow reduction Wolf-Kishner reduction Clemmensen reduction

Problem 17 Given the bong energies of H-H & Cl-Cl are 430 kJmol-1 & 240 kJ mol-1 respectively & ΔHf for HCl is -90 kJmol-1, bond enthalpy of HCl is 380 kJ mol-1 425 kJ mol-1 245 kJ mol-1 290 kJ mol-1

Problem 18 Which of the following represent the correct order of the acidity in the given compounds ? FCH2COOH > CH3COOH > BrCH2COOH > ClCH2COOH BrCH2COOH > ClCH2COOH > FCH2COOH > CH3COOH FCH2COOH > ClCH2COOH > BrCH2COOH > CH3COOH CH3COOH > BrCH2COOH > ClCH2COOH > FCH2COOH

Problem 19 If there is no rotation of the plane polarized light by a compound in a specific solvent, through to be chiral, it may mean that The compound is certainly meso There is no compound in the solvent The compound may be a racemic mixture The compound is certainly a chiral.

Problem 20 CH3-CHCl-CH2-CH3 has a chiral center. Which one of the following represented its R- configuration ? a. b. c. d.

Problem 21 Which of the following vitamin is water soluble ? vitamin E vitamin K vitamin A vitamin B

Problem 22 Identify the correct order of the size of the following : Ca2+ < K+ < Ar < Cl- < S2- Ar < Ca2+ < K+ < Cl- < S2- Ca2+ < Ar < K+ < Cl- < S2- Ca2+ < K+ < Ar < S2-< Cl-

Problem 23 0.5molar aqueous solution of a week acid (HX) is 20% ionized. If Kf for water is1.86 K kgmol-1 , the lowering in freezing point of the solution is 0.56 K 1.12 K -0.56 K -1.12 K

Problem 24 Sulphide ores of metal are usally concentrated by froth flotation process. Which one of the following sulphide ores offer an exception & is concentrated by chemical leaching ? Galena Copper pyrite Sphalerite Argentite.

Problem 25 If 60% of a first order reaction was completed in 60 minutes , 50% of the same reaction would be completed in approximately 45 minutes 60 minutes 40 minutes 50 minutes (log4=0.60, log 5=0.69)

Problem 26 Which of the following will give a pair of enantiomorphs ? [Cr(NH3)6][Co(CN)6] [Co(en)2Cl2]Cl [Pt(NH3)4][PtCl6] [Co(NH3)4Cl2]NO2 (en=NH2CH2CH2NH2)

Problem 27 If NaCl is doped with 10-16 mol% of SrCl2, the concentration of cation vacancies will be (NA=6.02 X 1023 mol-1) 6.02 X 1016 mol-1 6.02 X 1017 mol-1 6.02 X 1014 mol-1 6.02 X 1015 mol-1

Problem 28 The d electron configurations of Cr2+, Mn2+, Fe2+ & Ni2+ are 3d4, 3d5, 3d6, & 3d8respectively. which one of the following aqua complex will exhibit the minimum paramagnetic behavior ? [Fe(H2O)6]2+ [Ni(H2O)6]2+ [Cr(H2O)6]2+ [Mn(H2O)6]2+ (At.No. Cr=24, Mn=25, Fe=26, Ni=28)

Problem 29 In which of the following the hydration energy is higher than the lattice energy ? MgSo4 RaSO4 SrSO4 BaSO4

Problem 30 Which of the compounds with molecular formula C5H10 yields acetone to ozonolysis ? 3-methyl-1-butene Cyclopentane 2-methyl-1-butene 2-methyl-2-butene

Problem 31 With which of the following electronic configuration an atom has the lowest ionization enthalpy? 1s2 2s2 2p2 1s2 2s2 2p5 3s1 1s2 2s2 2p6 1s2 2s2 2p5

Problem 32 With which of the following ionic species has the greatest proton affinity to form stable compound ? HH2- F- I- HS-

Problem 33 The following equilibrium constants are given : The equilibrium constant for the oxidation of NH3 by oxygen to give NO is K2K32/K1 K22K3/K1 K1K2/K3 K2K33/K1

Problem 34 Which one of the following ions is the most stable in aqueous solution ? V3+ Ti3+ Mn3+ Cr3+ ( at. No. Ti=22 , V= 23, Cr=24, Mn=25)

Problem 35 The correct order of C-O bond length among CO, CO32- , CO2 is CO < CO32- < CO2 CO32- < CO2< CO CO < CO2 < CO32- CO2< CO32- < CO

Problem 36 Which one of the following orders correctly represents the increasing acidic strength of the given acids ? HOClO < HOCl < HOClO3 < HOClO2 HOClO2 < HOClO3 < HOClO < HOCl HOClO3 < HOClO2 < HOClO < HOCl HOCl < HOClO < HOClO2 < HOClO3.

Problem 37 Which one of the following on treatment with 50% aqueous solution hydroxide yields the corresponding alcohol & acid ? C6H5CHO CH3CH2CH2CHO C6H5 CH2CHO

Problem 38 For I-, Cl-, Br- , the increasing order of nucleophilicity would be Cl- < Br- < I- I- < Cl- < Br- Br- < Cl- < I- I- < Br- < Cl-

Problem 39 Calculate the pOH of a solution at 25°C that contain 1X10-10 M of hydronium ions, i.e. H3O+ 4.000 9.000 1.000 7.000

Problem 40 Consider the following sets of quantum numbers: Which of the following sets of quantum number is not possible? (i), (ii), (iii) & (iv) (ii), (iv) & (v) (i) & (ii) (ii), (iii) & (iv)

Problem 41 The equilibrium constant of the reaction: Cu(s) + 2Ag+(aq)-> Cu2+ (aq) + 2Ag (s) E0 =0.46V at 298K is 2.0 X 1010 4.0 X 1010 4.0 X 1015 2.4 X 1010

Problem 42 Which one of the following polymers prepared by condensation polymerization ? Teflon Natural rubber Styrene Nylon-66

Problem 43 The order of decreasing reactivity towards an electrophilic reagent, for the following would be Benzene Toluene Chlorobenzene Phenol (ii) > (iv) > (i) >(iii) (iv) > (iii)> (ii) >(i) (iv) >(ii) >(i)> (iii) (i) >(ii) >(iii)> (iv)

Problem 44 Which one of the following anions is present in the structure of silicates ? (Si2O52-)n (SiO32-)n SiO44- Si2O76-

Problem 45 An element , X has the following isotopic composition 200X:90 % 199X:8.0 % 202X:2.0 % The weighted average atomic mass of the naturally occurring element X is closed to 201 amu 202 amu 199 amu 200 amu

Problem 46 The fraction of total volume occupied by the atoms present in a simple cube is a. b. c. d.

Problem 47 In the reaction Which of the following compounds will be formed? a. b. c. d.

Problem 48 The product formed in Aldol condensation is A β- hydroxyaldehyde or a β- hydroxyketone An α- hydroxyaldehyde or ketone An α, β-unsaturated ester A β- hydroxyl acid.

Problem 49 The number of moles of KMnO4 that will be needed to react with one mole of sulphite ion in acidic solution is 4/5 2/5 1 3/5

Problem 50 Identify the incorrect statement among the following : Lanthanoid contraction is the accumulation of successive shrinkages. As a result of lanthanoid contraction, the properties of 4d series of the transition elements have no similarities with the 5d series of elements. Shielding power of 4f electrons is quite weak. There is a decrease in the radii of the atoms or ions as one proceeds from La to Lu.

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AIPMT Chemistry 2007

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