JEE MAIN - Chemistry (2007)

• 1

  The compound formed as a result of oxidation of ethyl benzene by KMnO₄ is :

  回答

  (C)

  benzoic acid
• 2

  Which one of the following conformation of cyclohexane is chiral?

  回答

  (A)

  Twist boat
• 3

  Presence of a nitro group in a benzene ring

  回答

  (D)

  deactivates the ring towards electrophilic substitution
• 4

  In a sautrated solution of the sparingly soluble strong electrolyte AgIO₃ (Molecular mass = 283) the equilibrium which sets in is
  AgIO_3(s) $$\leftrightharpoons$$ Ag⁺(aq) + $$IO_3^-$$
  If the solubility product constant K_sp of AgIO₃ at a given temperature is 1.0 $$\times$$10⁻⁸, what is the mass of AgIO₃ contained in 100 ml of its saturated solution?

  回答

  (B)

  2.83 × 10⁻³ g
• 5

  The pK_a of a weak acid (HA) is 4.5. The pOH of an aqueous buffered solution of HA in which 50% of the acid is ionized is :

  回答

  (D)

  9.5
• 6

  The first and second dissociation constants of an acid H₂A are 1.0 $$\times$$ 10⁻⁵ and 5.0 $$\times$$ 10⁻¹⁰ respectively. The overall dissociation constant of the acid will be :

  回答

  (C)

  5.0 $$\times$$ 10⁻¹⁵
• 7

  Identify the correct statement regarding a spontaneous process :

  回答

  (A)

  For a spontaneous process in an isolated system, the change in entropy is positive
• 8

  In conversion of lime-stone to lime,
  CaCO₃(s) $$\to$$ CaO(s) + CO₂ (g) the vales of ∆H° and ∆S° are +179.1 kJ mol−1 and 160.2 J/K respectively at 298 K and 1 bar. Assuming that ∆H° do not change with temperature, temperature above which conversion of limestone to lime will be spontaneous is :

  回答

  (D)

  1118 K
• 9

  The reaction of toluene with Cl₂ in presence of FeCl₃ gives predominantly

  回答

  (C)

  o-and p-chlorotoluene
• 10

  The actinoids exhibits more number of oxidation states in general than the lanthanoids. This is because :

  回答

  (D)

  the 5f orbitals extend further from the nucleus than the 4f orbitals
• 11

  The stability of dihalides of $$Si,Ge,Sn$$ and $$Pb$$ increases steadily in the sequence :

  回答

  (D)

  $$Si{X_2} < < Ge{X_2} < < Sn{X_2} < < Pb{X_2}$$
• 12

  

  回答

  (A)

  $$3$$ - enthyl - $$4$$ - $$4$$ - dimethylheptane
• 13

  Which of the following molecules is expected to rotate the plane of plane - polarized light?

  回答

  (B)

  
• 14

  Assuming that water vapour is an ideal gas, the internal energy change $$\left( {\Delta U} \right)$$ when $$1$$ mol of water is vapourised at $$1$$ bar pressure and $${100^ \circ }C$$ (Given : molar enthalpy of vapourisation of water at $$1$$ bar and $$373$$ $$K$$ $$ = 41\,kJ\,mo{l^{ - 1}}\,$$
  and $$R = 8.3\,J\,mo{l^{ - 1}}\,{K^{ - 1}}$$ )

  回答

  (D)

  $$37.904\,kJ\,mo{l^{ - 1}}$$
• 15

  The secondary structure of a protein refers to

  回答

  (A)

  $$\alpha$$-helical backbone
• 16

  In the chemical reaction,
  CH₃CH₂NH₂ + CHCl₃ + 3KOH $$\to$$ (A) + (B) + 3H₂O, the compound (A) and (B) are respectively

  回答

  (D)

  C₂H₅NC and 3KCl
• 17

  Which one of the following is the strongest base in aqueous solution?

  回答

  (C)

  Dimethylamine
• 18

  In the following sequence of reactions,
  CH₃CH₂OH $$\buildrel {P + {I_2}} \over \longrightarrow $$ A $$\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{ether}^{Mg}} $$ B $$\buildrel {HCHO} \over \longrightarrow $$ C $$\buildrel {{H_2}O} \over \longrightarrow $$ D
  the compound ‘D’ is

  回答

  (C)

  n-propyl alcohol
• 19

  Which of the following is the correct order of decreasing S_N2 reactivity?

  回答

  (B)

  RCH₂X > R₂CHX > R₃CX
• 20

  Which one of the following has a square planar geometry?

  回答

  (D)

  [PtCl₄]^2-
• 21

  Identify the incorrect statement among the following :

  回答

  (D)

  4f and 5f orbitals are equally shielded
• 22

  Regular use of which of the following fertilizer increases the acidity of soil?

  回答

  (D)

  Ammonium sulphate
• 23

  Which of the following nuclear reactions will generate an isotope?

  回答

  (A)

  neutron particle emission
• 24

  A radioactive element gets spilled over the floor of a room. Its half-life period is 30 days. If the initial activity is ten times the permissible value, after how many days will it be safe to enter the room?

  回答

  (D)

  100 days
• 25

  Consider the reaction, 2A + B $$\to$$ products. When concentration of B alone was doubled, the half-life did not change. When the concentration of A alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is

  回答

  (A)

  L mol^-1 s^-1
• 26

  The energies of activation for forward and reverse reactions for A₂ + B₂ $$\leftrightharpoons$$ 2AB are 180 kJ mol⁻¹ and 200 kJ mol⁻¹ respectively. The presence of catalyst lowers the activation energy of both (forward and reverse) reactions by 100 kJ mol⁻¹. The enthalpy change of the reaction ( A₂ + B₂ $$\to$$ 2AB) in the presence of catalyst will be (in kJ mol⁻¹)

  回答

  (D)

  20
• 27

  The cell, Zn | Zn²⁺ (1M) || Cu²⁺ (1M) | Cu($$E_{cell}^o$$ = 1.10V) was allowed to be completely discharged at 298 K. The relative concentration of Zn²⁺ to Cu²⁺ $$\left[ {{{\left[ {Z{n^{2 + }}} \right]} \over {\left[ {C{u^{2 + }}} \right]}}} \right]$$ is

  回答

  (C)

  10^37.3
• 28

  The equivalent conductances of two strong electrolytes at infinite dilution in H₂O (where ions move freely through a solution) at 25^oC are given below:
  $$ \wedge _{C{H_3}COONa}^o$$ = 91.0 S cm²/equiv
  $$ \wedge _{HCl}^o$$ = 426.2 S cm²/equiv
  What additional information/quantity one needs to calculate $$ \wedge ^o$$ of an aqueous solution of acetic acid?

  回答

  (B)

  $$ \wedge ^o$$ of NaCl
• 29

  A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of 290 mm at 300 K. The vapour pressure of propyl alcohol is 200 mm. If the mole fraction of ethyl alcohol is 0.6, its vapour pressure (in mm) at the same temperature will be

  回答

  (B)

  350
• 30

  A 5.25 % solution of a substance is isotonic with a 1.5% solution of urea (molar mass = 60 g mol⁻¹) in the same solvent. If the densities of both the solutions are assumed to be equal to 1.0 g cm⁻³, molar mass of the substance will be

  回答

  (D)

  210.0 g mol⁻¹
• 31

  Which of the following reactions will yield 2, 2-dibromopropane?

  回答

  (B)

  CH₃ - C $$\equiv$$ CH + 2HBr $$\to$$
• 32

  Which of the following hydrogen bonds is the strongest?

  回答

  (B)

  F−H…….F
• 33

  In which of the following ionization processes, the bond order has increased and the magnetic behaviour has changed?

  回答

  (C)

  $$NO \to NO^+$$
• 34

  The charge/size ratio of a cation determines its polarizing power. Which one of the following sequences represents the increasing order of the polarizinig order of the polarizing power of the cationic species, K⁺, Ca²⁺, Mg²⁺, Be²⁺?

  回答

  (B)

  K⁺ < Ca²⁺ < Mg²⁺ < Be²⁺
• 35

  Which of the following species exhibits the diamagnetic behaviour?

  回答

  (A)

  $$O_2^{2−}$$
• 36

  Which of the following sets of quantum numbers represents the highest energy of an atom?

  回答

  (C)

  n = 3, l = 2, m = 1, s = +1/ 2
• 37

  In the reaction
  
  2Al(s) + 6HCl(aq) $$\to$$ 2Al³⁺ (aq) + 6Cl^-(aq) + 3H₂(g)

  回答

  (A)

  11.2 L H₂(g) at STP is produced for every mole HCl(aq) consumed
• 38

  The average marks of boys in a class is 52 and that of girls is 42. The average marks of boys and girls combined is 50. The percentage of boys in the class is

  回答

  (A)

  80