JEEMain-2015 Solutions Chemistry
Transcription
JEEMain-2015 Solutions Chemistry
JEE MAIN 2015 CHEMISTRY QUESTION PAPER & SOLUTION 61. The vapour pressure of acetone at 20o C is 185 torr. When 1.2 g of a non-volatile substance was dissolved in 100g of acetone at 20o C, its vapour pressure was 183 torr. The molar mass (g mol1 ) of the substance is (A) 488 (B) 32 Solution: (C) (C) 64 (D) 128 Po (acetone) 185 torr Now, P o (acetone) P(acetone) P o (acetone) 1.2 185 183 M 1.2 100 185 M 58 (M 64) Xsolute 62. 3 g of activated charcoal was added to 50 mL of acetic acid solution (0.06N) in a flask. After an hour its was filtered and the strength of the filtrate was found to be 0.042 N. The amount of acetic acid absorbed (per gram of charcoal) is: (A) 54 mg (B) 18 mg (C) 36 mg (D) 42 mg Solution: (B) Millieq. Of Acetic acid before absorption 0.06N 50 3 meq Millieq of acetic acid after absorption 0.042 50 2.1 meq Thus, millieq of CH3COOH absorbed (3 2.1) meq 0.9 meq 10 Thus mass of CH3COOH absorbed by 3g charcoal 0.9 mg 1 0.9 60 mass of CH3COOH absorbed/gram of charcoal approximate analysis. 3 63. Which of the following is the energy of a possible excited state of hydrogen? (A) 6.8 eV (B) 13.6 eV (C) 6.8 eV (D) 3.4 eV Solution (D) Energy of electron is 2nd orbit of H atom 3.4 eV 64. Which among the following is the most reactive? (A) ICl (B) Cl2 (C) Br2 (D) I2 Solution: (A) Since, qut of all the given molecules i.e. ICl, Cl2,Br2, only ICl is polar, thus most reactive I Cl 65. Which polymer is used in the manufacture of paints and lacquers? (A) Poly vinyl chloride (B) Bakelite (C) Glyptal Solution : (A) PVC is used in paints (D) Polypropene 1 66. The molecular formula of a commercial resin used for exchanging ions in water softening is C8H7SO3Na (Mol. wt. 206) . What would be the maximum uptake of Ca 2 ions by the resin when expressed in mole per gram resin? 1 1 1 2 (A) (B) (C) (D) 412 103 206 309 Solution: (A) The compound formed nuclear C8H7SO3Na is reacted with Ca 2 ion is (C8H7SO3 )2 Ca i.e., 2 mole of resi. Reacts with 1 mole of Ca 2 ion i.e., 2 206g combines with 1 mole of Ca 2 ion 1 i.e., 1g of resi. combines with moles of Ca 2 412 67. In Carius method of estimation of halogens, 250 mg of an organic compound gave 141 mg of AgBr. The percentage of bromine in the compound is (at.mass Ag 108; Br 80) (A) 60 (B) 24 (C) 36 (D) 48 Solution: (B) 80 141 80 weight of AgBr 100 24% % of Br 100 188 250 188 weight of organic compound 68. Assertion: Nitrogen and Oxygen are the main components in the atmosphere but these do not react to form oxides of nitrogen. Reason: The reaction between nitrogen and oxygen requires high temperature. (A) Both the assertion and reason are incorrect (B) Both assertion and reason are correct, and the reason is the correct explanation for the assertion (C) Both assertion and reason are correct, but the reason is not the correct explanation for the assertion (D) The assertion is incorrect, but the reason is correct Solution: (B) Both statement are correct & IInd state also explain the reason of first statement N2 O2 NO (highly endothermic process) At low temperature N2 & O2 cannot React to each other. But at high temperature N2 & O2 can reacts. 69. The following reaction is performed at 298K. 2NO(g) O2(g) 2NO2(g) The standard free energy of formation of NO(g) is 86.6 kJ/mol at 298K. What is the standard free energy of formation of NO2(g) at 298K ? (Kp 1.6 1012 ) (A) 0.5[2 86,600 R(298) ln(1.6 1012 )] (B) R(298) ln(1.6 1012 ) 86600 (C) 86600 R(298) ln(1.6 1012 ) (D) 86600 Solution: (A) For the given reaction 2NO(g) O2(g) 2NO2(g) Goreaction R(298) ln(1.6 1012 ) 2 ln(1.6 1012 ) R(298) Now, from herses low of constant heat summation Goreaction Goproducts Goreac tants R(298) ln(1.6 1012 ) 2 GoNO2 2 GoNO 1 GoO 2 R(298) ln(1.6 1012 ) 2 GoNO 2 86600 0 2 1 2 86600 R(298) ln(1.6 1012 ) 2 70. Which one of the following alkaline earth metal sulphates has its hydration enthalpy greater than its lattice enthalpy? (A) SrSO4 (B) CaSO4 (C) BeSO4 (D) BaSO4 Solution: (C) For BeSO4 , hydration enthalpy is greater than lattice enthalpy, i.e. it is soluble salt. GoNO 2 71. The number of geometric isomers that can exist for square planar [Pt(Cl)(py)(NH3 )(NH2OH) is (py pyridine) : (A) 6 (B) 2 (C) 3 (D) 4 Solution: (C) No. of geometrical isomers of Pt(Cl)(Py)(NH3 )(NH2OH) Py NH3 NH3 Cl Cl Pt HONH2 Pt Pt Py Py NH3 NH2OH Cl NH2OH Possible isomers are =3 72. The synthesis of alkyl fluorides is best accomplished by: (A) Swarts reaction (B) Free radical fluorination (C) Sandmeyer’s reaction (D) Finkelstein reaction Solution: (A) R X AgF R F Ag x (ppt) Swarts reaction) 73. The intermolecular interaction that is dependent on the inverse cube of distance between the molecules is: (A) hydrogen bond (B) ion – ion interaction (C) ion – dipole interaction (D) London force Solution: (A) According to our point of view Hydrogen bond is special case of dipole-dipole interaction where molecule do not rotate thus, 1 Energy r3 74. In the context of the Hall-Heroult process for the extraction of Al, which of the following statements is false? (A) Na 3 AlF6 serves as the electrolyte (B) CO and CO2 are produced in this process (C) Al2O3 is mixed with CaF2 which lowers the melting point of the mixture and brings conductivity 3 (D) Al3 is reduced at the cathode to form Al Solution: (A) In case of electrolysis of Al2O3 , Cryolite is added to solution to decreases the M.P. but Na3AlF6 is not considered as electrolyte. 75. Which of the following compound will exhibit geometrical isomerism? (A) 1, 1-Diphenyl-1-propane (B) 1-Phenyl – 2 – butane (C) 3-Phenyl-1-butene (D) 2-Phenyl -1-butene Solution: (B) Structure of 1-phenyl-2-butene H Ph H Thus, it will exhibit GI. 76. The ionic radii (in Å) of N3 ,O2 and F are respectively: (A) 1.71, 1.36 and 1.40 (B) 1.36, 1.40 and 1.71 (C) 1.36, 1.71 and 1.40 (D) 1.71, 1.40 and 1.36 Solution: (D) Ionic size of N3 O2 F 77. From the following statements regarding H2O2, choose the incorrect statement: (A) It has to be kept away from dust (B) It can act only as an oxidizing agent (C) It decomposes on exposure to light (D) It has to be stored in plastic or wax lined glass bottles in dark Solution: (B) H2O2 can act both as (oxidizing agent) as well as Reducing agent 78. Higher order (>3) reactions are rare due to (A) loss of active species on collision (B) low probability of simultaneous collision of all the reacting species (C) increase in entropy and activation energy as more molecules are involved (D) shifting of equilibrium towards reactants due to elastic collisions Solution: (B) Higher order reactions are how because of low probability of collision of all the reacting species, simultaneously. 79. Match the catalyst to the correct processes: Catalyst Process (A) TiCl3 (i) Wacker process (B) PdCl2 (ii) Ziegler – Natta polymerization (C) CuCl2 (iii) Contact process (D) V2O5 (iv) Deacon’s process (A) (A)-(iii), (B)-(i), (C)-(ii), (D)-(iv) (B) (A)-(iii), (B)-(ii), (C)-(iv), (D)-(i) (C) (A)-(ii), (B)-(i), (C)-(iv), (D)-(iii) (D) (A)-(ii), (B)-(iii), (C)-(iv), (D)-(i) Solution: (C) Defined catalyst in Different process. 80. Which one has the highest boiling point? (A) Xe (B) He 4 (C) Ne (D) Kr Solution: (A) Boiling Point Molar mass i.e. Xe has highest B.P. 81. In the reaction NH2 NaNO /HCl CuCN/KCN Δ 2 D E + N2 o 0-5 C CH3 the product E is COOH CH3 (A) (B) CH3 CN CH3 H3C (C) (D) Solution: (D) NH2 N 2 Cl NaNO /HCl + N2 0-5 C CH3 CH3 CN CuCN/KCN Δ 2 o CH3 CH3 (E) (D) 82. Which of the following compounds is not coloured yellow? (A) BaCrO4 (B) Zn2[Fe(CN)6 ] (C) K3[Co(NO2 )6 ] Solution: (B) (D) (NH4 )3[As(Mo3O10 )4 ] 83. Sodium metal crystallizes in a body centred cubic lattice with a unit cell edge of 4.29Å. The radius of sodium atom is approximately: (A) 0.93Å (B) 1.86 Å (C) 3.22 Å (D) 5.72 Å Solution: (B) For BCC 4r 3a 4rNa 3 4.29 rNa 3 4.29 Å=1.86Å 4 5 84. The standard Gibbs energy change at 300 K for the reaction 2A B C is 2494.2J. At given 1 1 time, the composition of the reaction mixture is [A] ,[B] 2 and [C] . The reaction 2 2 proceeds in the: R 8.314J/K mol, e 2.718] (A) reverse direction because Q Kc (B) Forward direction because Q Kc (C) Reverse direction because Q Kc (D) forward direction because Q Kc Solution: (C) 2A Go 2494.2J B C 1 1 Given [A] , [B] 2, [C] 2 2 1 2 [B] [C] 2 4 Qc 2 2 [A] 1 2 Go RT ln Kc 2494.2 8.314 300 ln Kc 2494.2 ln Kc 1 8.314 300 1 1 Kc e1 e 2.718 Qc KC so reaction proceeds in backward direction. 85. Which compound would give 5-keto-2-methyl hexanal upon ozonolysis? CH3 CH3 CH3 CH3 CH3 H3C (A) (B) Solution: (C) CH3 O3/Zn-H2O CH3 (C) (D) CH3 O CH3 - C - CH2 - CH2 - CH- CHO CH3 CH3 5-keto-2-methyl hexanal 86. Which of the following compound is not an antacid? (A) Ranitidine (B) Aluminium hydroxide (C) Cimetidine Solution: (D) Phenelzine is anti-depressant. KMnO (D) Phenelzine SOCl H /Pd BaSO4 2 2 4 A B C, 87. In the following sequence of reactions Toluene product C is: (A) C2H5CHO 6 (B) C6H5COOH (C) C6H5CH3 (D) C6H5CH2OH the Solution: (A) O CH3 KMnO 4 CHO C - Cl CH3 SOCl 2 H /Pd-BaSO 2 4 Benzaldehyde 88. Which of the vitamins given below is water soluble? (A) Vitamin K (B Vitamin C (C) Vitamin D Solution: (B) Vitamin C is soluble in water. (D) Vitamin E 89. The colour of KMnO4 is due to: (A) * transition (B) M L charge transfer transition (C) d – d transition (D) L M charge transfer transition Solution: (D) In case of KMnO4 there is absence of vacant d-orbital so. charge transfer spetra from 'L M' is Responsible for Colour. 90. Two Faraday of electricity is passed through a solution of CuSO4. The mass of copper deposited at the cathode is (at. mass of Cu 63.5 amu) (A) 127 g (B) 0 g (C) 63.5 g (D) 2 g Solution: (C) Cu2 2e Cu 2 mole e is required for depositing 1 mole Cu . i.e. 2F charge is required for depositing 63.5 gm Cu 7