JEE MAIN - Chemistry (2005)

• 1

  An amount of solid NH4HS is placed in a flask already containing ammonia gas at a certain temperature and 0.50 atm. Pressure. Ammonium hydrogen sulphide decomposes to yield NH₃ and H₂S gases in the flask. When the decomposition reaction reaches equilibrium, the total pressure in the flask rises to 0.84 atm. The equilibrium constant for NH₄HS decomposition at this temperature is :

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  (B)

  0.11
• 2

  Consider an endothermic reaction, X $$\to$$ Y with the activation energies E_b and E_f for the backward and forward reactions, respectively. In general :

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  (A)

  E_b < E_f
• 3

  Consider the reaction: N₂ + 3H₂ $$\to$$ 2NH₃ carried out at constant temperature and pressure. If $$\Delta H$$ and $$\Delta U$$ are the enthalpy and internal energy changes for the reaction, which of the following expressions is true?

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  (B)

  $$\Delta H$$ < $$\Delta U$$
• 4

  If the bond dissociation energies of XY, X₂ and Y₂ (all diatomic molecules) are in the ratio of 1:1:0.5 and $$\Delta H_f$$ for the formation of XY is -200 kJ mole^-1. The bond dissociation energy of X₂ will be :

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  (D)

  800 kJ mol^-1
• 5

  The solubility product of a salt having general formula MX₂, in water is: 4 $$\times$$ 10^-12 . The concentration of M²⁺ ions in the aqueous solution of the salt is :

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  (C)

  1.0 $$\times$$ 10^-4 M
• 6

  The exothermic formation of ClF₃ is represented by the equation:
  Cl₂ (g) + 3F₂ (g) $$\leftrightharpoons$$ 2ClF₃ (g); $$\Delta H$$ = -329 kJ
  Which of the following will increase the quantity of ClF₃ in an equilibrium mixture of Cl₂, F₂ and ClF₃?

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  (D)

  Adding F₂
• 7

  For the reaction 2NO₂ (g) $$\leftrightharpoons$$ 2NO (g) + O₂ (g), (K_c = 1.8 $$\times$$ 10^-6 at 184^oC) (R = 0.0831 kJ/(mol. K))
  When K_p and K_c are compared at 184^oC , it is found that :

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  (A)

  K_p is greater than K_c
• 8

  What is the conjugate base of OH^-?

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  (D)

  O^-2
• 9

  Hydrogen ion concentration in mol / L in a solution of pH = 5.4 will be :

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  (A)

  3.98 $$\times$$ 10^-6
• 10

  Which one of the following species is diamagnetic in nature?

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  (B)

  H₂
• 11

  Due to the presence of an unpaired electron, free radicals are:

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  (A)

  Chemically reactive
• 12

  Reaction of one molecule of HBr with one molecule of 1,3-butadiene at 40^oC gives predominantly

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  (B)

  1-bromo-2-butene under thermodymically controlled conditions
• 13

  Of the five isomeric hexanes, the isomer which can give two monochlorinated compounds is

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  (B)

  2, 3-dimethylbutane
• 14

  2 methylbutane on reacting with bromine in the presence of sunlight gives mainly

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  (B)

  2 – bromo -2 - methylbutane
• 15

  Acid catalyzed hydration of alkenes except ethene leads to the formation of

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  (D)

  mixture of secondary and tertiary alcohols
• 16

  Which types of isomerism is shown by 2,3-dichlorobutane?

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  (B)

  Optical
• 17

  Which types of isomerism is shown by 2,3-dichlorobutane?

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  (B)

  Optical
• 18

  Benzene and toluene form nearly ideal solutions. At 20 ^oC, the vapour pressure of benzene is 75 torr and that of toluene is 22 torr. The partial vapour pressure of benzene at 20 ^oC for a solution containing 78 g of benzene and 46 g of toluene in torr is

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  (A)

  50
• 19

  Equimolar solutions in the same solvent have

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  (C)

  Same boiling and same freezing points
• 20

  Amongst the following the most basic compound is

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  (A)

  benzylamine
• 21

  Amongst the following the most basic compound is

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  (A)

  benzylamine
• 22

  Which one of the following methods is neither meant for the synthesis nor for separation of amines?

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  (C)

  Wurtz reaction
• 23

  An organic compound having molecular mass 60 is found to contain C = 20%, H = 6.67% and N = 46.67% while rest is oxygen. On heating it gives NH₃ along with a solid residue. The solid residue give violet colour with alkaline copper sulphate solution. The compound is

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  (C)

  (NH₂)₂CO
• 24

  In both DNA and RNA, heterocyclic base and phosphate ester linkages are at-

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  (C)

  $$C_1^{'}$$ and $$C_5^{'}$$ respectively of the sugar molecule
• 25

  The decreasing order of nucleophilicity among the nucleophiles
  
  

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  (A)

  $$\left( C \right),\left( B \right),\left( A \right),\left( D \right)$$
• 26

  The reaction
  
  
  
  is fastest when $$X$$ is

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  (D)

  $$Cl$$
• 27

  A schematic plot of $$ln$$ $${K_{eq}}$$ versus inverse of temperature for a reaction is shown below
  
  
  The reaction must be

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  (D)

  exothermic
• 28

  $$p$$-cresol reacts with chloroform in alkaline medium to give the compound A which adds hydrogen cyanide to form, the compound $$B.$$ The latter on acidic hydrolysis gives chiral carboxylic acid. The structure of the carboxylic acid is :

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  (C)

  
• 29

  The oxidation state of chromium in the final product formed the reaction between $$K{\rm I}$$ and acidified potassium dichromate solution is :

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  (A)

  $$+3$$
• 30

  On heating mixture of $$C{u_2}O$$ and $$C{u_2}S$$ will give :

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  (D)

  $$Cu + S{O_2}$$
• 31

  Calomel $$\left( {H{g_2}C{l_2}} \right)$$ on reaction with ammonium hydroxide gives :

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  (D)

  $$HgN{H_2}Cl$$
• 32

  Pick out the isoelectronic structure from the following :
  
  $$\eqalign{ & \left( i \right)\,\,\,\,\,\,C{H_3}^ + \cr & \left( {ii} \right)\,\,\,\,{H_3}{O^ + } \cr & \left( {iii} \right)\,\,\,N{H_3} \cr & \left( {iv} \right)\,\,\,\,C{H_3}^ - \cr} $$

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  (D)

  $$(ii), (iii)$$ and $$(iv)$$
• 33

  For a spontaneous reaction the ∆G , equilibrium constant (K) and $$E_{cell}^o$$ will be respectively

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  (A)

  -ve, >1, +ve
• 34

  Aluminium oxide may be electrolysed at 1000^oC to furnish aluminium metal (Atomic mass = 27 amu; 1 Faraday = 96,500 Coulombs). The cathode reaction is Al³⁺ + 3e^- $$\to$$ Al^o To prepare 5.12 kg of aluminium metal by this method would require

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  (A)

  5.49 $$\times$$ 10⁷ C of electricity
• 35

  The highest electrical conductivity of the following aqueous solutions is of :

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  (D)

  0.1 M difluoroacetic acid
• 36

  Electrolyte:	KCl	KNO3	HCl	NaOAc	NaCl
  $${ \wedge ^\infty }(Sc{m^2}mo{l^{ - 1}}):$$	149.9	145	426.2	91	126.5

  Calculate $$ \wedge _{HOAc}^\infty $$ Using appropriate molar conductances of the electrolytes listed above at infinite dilution in H₂O at 25^oC

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  (C)

  390.7
• 37

  Hydrogen bomb is based on the principle of

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  (C)

  Nuclear fusion
• 38

  A reaction involving two different reactants can never be

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  (A)

  Unimolecular reaction
• 39

  The photon of hard gamma radiation knocks a proton out of $${}_{12}^{24}Mg$$ nucleus to form

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  (C)

  the nuclide $${}_{11}^{23}Na$$
• 40

  t_1/4 can be taken as the time taken for the concentration of a reactant to drop to $$3 \over 4$$ of its initial value. If the rate constant for a first order reaction is K, the t_1/4 can be written as

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  (B)

  0.29 / K
• 41

  The lanthanide contraction is responsible for the fact that :

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  (C)

  Zr and Hf have about the same radius
• 42

  Which of the following factors may be regarded as the main cause of lanthanide contraction?

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  (C)

  Poorer shielding of 5d electrons by 4f electrons
• 43

  The IUPAC name of the coordination compound K₃[Fe(CN)₆] is

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  (B)

  Potassium hexacyanoferrate (III)
• 44

  The oxidation state of Cr in [Cr(NH₃)₄Cl₂]⁺ is :

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  (A)

  +3
• 45

  The value of the ‘spin only’ magnetic moment for one of the following configurations is 2.84 BM. The correct one is :

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  (A)

  d⁴ (in strong ligand field)
• 46

  Which one of the following cyano complexes would exhibit the lowest value of paramagnetic behaviour?
  (At. No. Cr = 24, Mn = 25, Fe = 26, Co = 27)

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  (D)

  [Co(CN)₆]^-3
• 47

  Tertiary alkyl halides are practically inert to substitution by S_N2 mechanism because of

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  (D)

  steric hindrance
• 48

  Elimination of bromine from 2-bromobutane results in the formation of-

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  (B)

  predominantly 2-butene
• 49

  Elimination of bromine from 2-bromobutane results in the formation of-

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  (B)

  predominantly 2-butene
• 50

  Alkyl halides react with dialkyl copper reagents to give

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  (C)

  alkanes
• 51

  The best reagent to convert pent -3- en-2-ol into pent -3-en-2-one is

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  (D)

  Pyridinium chloro – chromate
• 52

  Among the following acids which has the lowest pK_a value?

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  (B)

  HCOOH
• 53

  Two solutions of a substance (non electrolyte) are mixed in the following manner. 480 ml of 1.5 M first solution + 520 ml of 1.2 M second solution. What is the molarity of the final mixture?

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  (B)

  1.344 M
• 54

  If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of the substance will

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  (D)

  decrease twice
• 55

  Of the following sets which one does NOT contain isoelectronic species?

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  (B)

  $$SO_3^{2 - }$$, $$CO_3^{2 - }$$, $$NO_3^{-}$$
• 56

  In a multi-electron atom, which of the following orbitals described by the three quantum members will have the same energy in the absence of magnetic and electric fields?
  (A) n = 1, l = 0, m = 0
  (B) n = 2, l = 0, m = 0
  (C) n = 2, l = 1, m = 1
  (D) n = 3, l = 2, m = 1
  (E) n = 3, l = 2, m = 0
  

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  (A)

  (D) and (E)
• 57

  Which of the following oxides is amphoteric in character?

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  (D)

  SnO₂
• 58

  In which of the following arrangements the order is NOT according to the property indicated against it?

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  (C)

  B < C < N < O Increasing first ionization enthalpy
• 59

  Lattice energy of an ionic compounds depends upon

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  (D)

  Charge on the ion and size of the ion