AIEEE 2005 CHEMISTRY PAPER

CHEMISTRY
76. The oxidation state of Cr in [Cr(NH3)4 Cl2]+ is
1) 0 2) +1 3) +2 4) +3
Ans. (4)
77. Which one of the following types of drugs reduces fever?
1) Tranquiliser 2) Antibiotic 3) Antipyretic 4) Analgesic
Ans. (3)
78. Which of the following oxides is amphoteric in character?
1) SnO2 2) SiO2 3) CO 2 4) Cao
m
Ans. (1)
o
.c
SnO 2 is an amphoteric oxide since it can reacts both with acid and bases.
79. Which one of the following species is diamagnetic in nature?
e
g
− + +
2) 3) 4)
1) H2 H2 He2
H2
a
Ans. (3) There is no unpaired electron in H2
p
80. If α is the degree of dissociation of Na2SO4, the vant Hoff’s factor (i) used for calculating the molecular mass is
e
1) 1 - 2α 2) 1 + 2α 3) 1-α 4) 1+α
e
Na 2SO 4 → 2 Na ( − ) + SO 4 2 −
Ans. (2)
ie
1-α α
2α
.a
i = l - α + 2α + α
i = l + 2α
81. Which of the following is a polyamide ?
w
1) Bakelite 2) Terylene 3) Nylon-66 4) Teflon
w
Ans. (3)
w
O O
– C – CH 2 – C – NH – CH 2 – NH –
4 6
82. Due to the presence of an unpaired electron, free radicals are:
1) Cations 2) Anions
3) Chemically inactive 4) Chemically reactive
Ans. (4)
0
83. For a spontaneous reaction the ∆ G, equilibrium constant (K) and ECell will be respectively
1) -ve, >1, -ve 2) -ve, <1, - ve 3) +ve, >1, -ve 4) -ve, >1, +ve
Ans. (4)
For Spontaneous process,
∆G = − ve, K > 1 and E o = + ve
cell
84. Hydrogen bomb is based on the principle of
1) artificial radioactivity 2) nuclear fusion 3) natural radioactivity 4) nuclear fission
Ans. (2)
85. An ionic compound has a unit cell consisting of A ions at the corners of a cube and B ions on the centres of the
faces of the cube. The empirical formula for this compound would be
1) A 3 B 2) AB 3 3) A2B 4) AB
Ans. (2)
1
Contribution of atom of ‘A’ at 8 corners of cube = x8=1
8
1
xc = 3
Contribution of atom of ‘B’ at six faces of cube =
2
∴ Formula of compound = 4B3
m
86. The highest electrical conductivity of the following equeous solutions is of
o
1) 0.1 M difluoroacetic acid 2) 0.1 M fluoroacetic acid
.c
2) 0.1 M chloroacetic acid 4) 0.1 M acetic acid
Ans. (1)
e
Difluoroacetic acid will be strongest acid due to electron withdrawing effect of two fluorine atoms so as it will
g
show maximum electrical conductivity.
a
87. Lattice energy of an ionic compound depends upon
p
1) Charge on the ion and size of the ion 2) Packing of ions only
e
3) Size of the ion only 4) Charge on the ion only
Ans. (1)
e
88. Consider an endothermic reaction X → Y with the activation energies Eb and Ef for the backward and forward
ie
reactions, respectively. In general
there is no definite relation between Eb and Ef 2) Eb + Ef
1)
.a
3) Eb>Ef 4) Eb< Ef
Ans. (4)
w
Eb
w
Ef
E Products
w
Reactions
Reaction Progress
89. Aluminium oxide may be electrolysed at 10000C to furnish aluminium metal (At. Mass = 27 amu; 1 Faraday =
96,500 Coulombs). The cathode reaction is Al 3+ + 3e − → Al 0 .
To prepare 5.12 kg of aluminium metal by this method would require
5.49 x 101 C of electricity 5.49 x 104 C of electricity
1) 2)
3) 1.83 x 107 C of electricity 5.49 x 107 C of electricity
4)
Ans. (4)
9 gm of Al requires 96500 C
5120 gms of Al requires ......?
(5.12 kg)
5120 x 96500
=
9
= 5.49 x 107 compounds
90. The volume of a colloidal particle, VC as compared to the volume of a solute particle in a true solution VS, could be
VC VC VC
VC -3
~ 103 2) VS ~ 10 3) VS ~ 10 4) VS ~ 1
1) 23
VS
Ans. (1)
For true solution the diameter range is 1 to < 10Å and for colloidal solution diameter range is 10 to 1000Å. Taking
the lower limits.
43
πr 3
VC 3 C  rC 
= 
=
4 3  rS 
VS πrS  
3
rC
Putting ratio of diameters in place of r
S
m
3
 10  3
Q Ratio of diameters =  1  = 10
o

CHEMISTRY
76. The oxidation state of Cr in [Cr(NH3)4 Cl2]+ is
1) 0 2) +1 3) +2 4) +3
Ans. (4)
77. Which one of the following types of drugs reduces fever?
1) Tranquiliser 2) Antibiotic 3) Antipyretic 4) Analgesic
Ans. (3)
78. Which of the following oxides is amphoteric in character?
1) SnO2 2) SiO2 3) CO 2 4) Cao
m
Ans. (1)
o
.c
SnO 2 is an amphoteric oxide since it can reacts both with acid and bases.
79. Which one of the following species is diamagnetic in nature?
e
g
− + +
2) 3) 4)
1) H2 H2 He2
H2
a
Ans. (3) There is no unpaired electron in H2
p
80. If α is the degree of dissociation of Na2SO4, the vant Hoff’s factor (i) used for calculating the molecular mass is
e
1) 1 - 2α 2) 1 + 2α 3) 1-α 4) 1+α
e
Na 2SO 4 → 2 Na ( − ) + SO 4 2 −
Ans. (2)
ie
1-α α
2α
.a
i = l - α + 2α + α
i = l + 2α
81. Which of the following is a polyamide ?
w
1) Bakelite 2) Terylene 3) Nylon-66 4) Teflon
w
Ans. (3)
w
O O
– C – CH 2 – C – NH – CH 2 – NH –
4 6
82. Due to the presence of an unpaired electron, free radicals are:
1) Cations 2) Anions
3) Chemically inactive 4) Chemically reactive
Ans. (4)
0
83. For a spontaneous reaction the ∆ G, equilibrium constant (K) and ECell will be respectively
1) -ve, >1, -ve 2) -ve, <1, - ve 3) +ve, >1, -ve 4) -ve, >1, +ve
Ans. (4)
For Spontaneous process,
∆G = − ve, K > 1 and E o = + ve
cell
84. Hydrogen bomb is based on the principle of
1) artificial radioactivity 2) nuclear fusion 3) natural radioactivity 4) nuclear fission
Ans. (2)
85. An ionic compound has a unit cell consisting of A ions at the corners of a cube and B ions on the centres of the
faces of the cube. The empirical formula for this compound would be
1) A 3 B 2) AB 3 3) A2B 4) AB
Ans. (2)
1
Contribution of atom of ‘A’ at 8 corners of cube = x8=1
8
1
xc = 3
Contribution of atom of ‘B’ at six faces of cube =
2
∴ Formula of compound = 4B3
m
86. The highest electrical conductivity of the following equeous solutions is of
o
1) 0.1 M difluoroacetic acid 2) 0.1 M fluoroacetic acid
.c
2) 0.1 M chloroacetic acid 4) 0.1 M acetic acid
Ans. (1)
e
Difluoroacetic acid will be strongest acid due to electron withdrawing effect of two fluorine atoms so as it will
g
show maximum electrical conductivity.
a
87. Lattice energy of an ionic compound depends upon
p
1) Charge on the ion and size of the ion 2) Packing of ions only
e
3) Size of the ion only 4) Charge on the ion only
Ans. (1)
e
88. Consider an endothermic reaction X → Y with the activation energies Eb and Ef for the backward and forward
ie
reactions, respectively. In general
there is no definite relation between Eb and Ef 2) Eb + Ef
1)
.a
3) Eb>Ef 4) Eb< Ef
Ans. (4)
w
Eb
w
Ef
E Products
w
Reactions
Reaction Progress
89. Aluminium oxide may be electrolysed at 10000C to furnish aluminium metal (At. Mass = 27 amu; 1 Faraday =
96,500 Coulombs). The cathode reaction is Al 3+ + 3e − → Al 0 .
To prepare 5.12 kg of aluminium metal by this method would require
5.49 x 101 C of electricity 5.49 x 104 C of electricity
1) 2)
3) 1.83 x 107 C of electricity 5.49 x 107 C of electricity
4)
Ans. (4)
9 gm of Al requires 96500 C
5120 gms of Al requires ......?
(5.12 kg)
5120 x 96500
=
9
= 5.49 x 107 compounds
90. The volume of a colloidal particle, VC as compared to the volume of a solute particle in a true solution VS, could be
VC VC

91. Consider the reaction : N 2 + 3H 2 → 2 NH 3 carried out at constant temperature and pressure. If ∆ H and ∆ U are
the enthalpy and internal energy changes for the reaction, which of the following expressions is true?
1) ∆ H > ∆ U ∆H < ∆U ∆H = ∆U ∆H = 0
2) 3) 4)
Ans. (2)
For the reaction
N 2( g ) + 3H 2(g) 2 NH 3( g )
∆ n = -2
∆ H = ∆ v + ∆ n RT
∆H < ∆v ∴ ∆ n = -2
92. The solubility product of a salt having general formula MX2, in water : 4 x 10-12. The concentration of M2+ ions in
the aqueous solution of the salt is
1) 4.0 x 10-10 M 2) 1.6 x 10-4 M 1.0 x 10-4 M 2.0 x 10-6 M
3) 4)
m
Ans. (3)
o
Let ‘S’ be the solubility of salt in mol. Lt–1
Mx2 → M 2+ + 2x (-)
.c
s s 2s
e
K S P = [ M 2 + ] [x ( − ) ]2
g
S . (2S)2
a
K S P = 4 S 3 = 4 x 10 -12
p
[ M 2+ ] = S = 10-4 M
e
93. Benzene and toluene form nearly ideal solutions. At 200C, the vapour pressure of benzene is 75 torr and that of
e
toluene is 22 torr. The partial vapour pressure of benzene at 200C for a solution containing 78 g of benzene and 46
g of toluene in torr is
ie
1) 53.5 2) 37.5 3) 25 4) 50
.a
Ans. (4)
78
=1
Moles of benzene =
78
w
46
Moles of Toluene = = 0.5
w
92
1
w
Mole fraction of Benzene XB =
1 + 0.5
2
XB =
3
0
Partial Vapour pressure of benzene, PB = PB × x B
2
P = 75 x = 50 torr.
3
94. Which one of the following statements is NOT true about the effect of an increase in temperature on the distribution
of molecular speeds in a gas?
1) The area under the distribution curve remains the same as under the lower temperature
2) The distribution becomes broader
3) The fraction of the molecules with the most probable speed increases
4) The most probable speed increases
Ans. (3)
95. For the reaction
2 NO( g ) + O2( g ),
2 NO2( g )
(Kc = 1.8 x 10-6 at 1840 C)
(R = 0.0831 kJ / (mol.K))
When Kp and Kc are compared at 1840 C it is found that
1) Whether Kp is greater than, less than or equal to Kc depends upon the total gas pressure
Kp = Kc
2)
3) Kp is less than Kc
4) Kp is greater than Kc
Ans. (4)
Kp & Kc are related
as, Κ p = K c (RT) ∆n
m
for the reaction,
o
2 NO( g ) + O2( g )
2 NO2( g )
.c
∆n = 1
1
∴ K p = K c (RT)
e
∴K p > K c
g
96. The exothermic formation of ClF3 is represented by the equation :
a
Cl2( g ) + 3F2( g ) 2ClF3( g ) ; ∆ rH = –329 kJ
p
Which of the following will increase the quentity of ClF3 in an equilibrium mixture of Cl2, F2 and ClF3?
e
1) Adding F2
e
2) Increasing the volume of the container
ie
3) Removing Cl2
4) Increasing the temperature
.a
Ans. (1)
Increase in the concentration of reactants at equilibrium into shift the equilibrium products side.
w
97. Hydrogen ion concentration in mol / L in a solution of pH = 5.4 will be :
w
1) 3.98 x 10-6 2) 3.68 x 10-6
3) 3.88 x 106 4) 3.98 x 108
w
Ans. (1)
[ H + ] = 10-pH
= 10 -5.4
= 10 -5 x 10 -0.4
= 10 -6 x 10 0.6
= (antilog 0.6) x 10-6
= 3.98 x 10-6 M
98. A reaction involving two different reactants can never be
1) bimolecular reaction 2) second order reaction
3) first order reaction 4) unimolecular reaction
Ans. (4)
The molecularity of such reaction can’t be less than 2
99. 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?
1) 2.70 M 2) 1.344 M
3) 1.50 M 4) 1.20 M
Ans. (2)
The value lies between M1 & M2
100. During the process of electrolytic refining of copper, some metals present as impurity settle as ‘anode mud’.
These are
1) Fe and Ni 2) Ag and Au
3) Pb and Zn 4) Sn and Ag
Ans. (2)
KNO3 HCl NaOAc NaCl
Electrolyte : KCl
m
Calculate Λ∞ HOAc using appropriate molar conductances of the
101. Λ∞ ( S cm 2 mol −1 ) : 149.9 145.0 426.2 91.0 126.5
o
electrolytes listed above at infinite dilution in H2O at 250C
.c
1) 217.5 2) 390.7 3) 552.7 4) 517.2
Ans. (2)
e
Λ∞ HOAc = Λ∞ NaOAc + Λ∞ HCl - Λ∞ NaCl
g
= 91 + 426.2 - 126.5
= 390.7
a
102. 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
p
of one mole of a substance will
e
1) be a function of the molecular mass of the substance
e
2) remain unchanged
3) increase two fold
ie
4) decrease twice
Ans. (4)
.a
1 atomic mass unit on the scale of 1/6 of C-12 = 2 amu on the scale of 1/12 of C-12
Numerically the mass of a substance will become half of the normal scale.
w
103. 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 ?
w
a) n = 1, l = 0, m = 0 b) n = 2, l = 0, m = 0 c) n = 2, l = 1, m = 1
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d) n = 3, l = 2, m = 1 e) n = 3, l = 2, m = 0
1) (d) and (e) 2) (c) and (d)
3) b) and c) 4) a) and b)
Ans. (1)
Q ‘n’ & ‘l’ values are same
104. Based on lattice energy and other considerations which one of the following alkali metal chlorides is expected to
have the highest melting point?
1) RbCl 2) KCl 3) NaCl 4) LiCl
Ans. (3)
LiCl have lowest melting point due to covalent nature and thereafter melting point decreases going down the
group because lattice enthalpies decreases and size of alkali metal increases.
105. A schematic plot of lnKeq l versus inverse of temperature for a reaction is shown below 6.0
6.0
In Key
2.0
1 −1
-3 -3
1.5 x 10 2.0 x 10
(K )
T
The reaction must be
1) highly spontaneous at ordinary temperature
2) one with negligible enthalpy change
3) endothermic
4) exothermic
m
Ans. (4)
o
∆H  1 1
k
.c
2
In k = R  T − T 
1 2
1
e
6 ∆H
[1.5 × 10 −3 − 2 × 10 −3 ]
=
In
2 R
g
∆H of reaction comes out to be -ve. Hence reaction is exothermic ∴ (4)


106. Heating mixture of Cu2O and Cu2S will give
Cu2SO3 2) CuO + CuS 3) Cu + SO3 4) Cu + SO2
1)
Ans. (4)
2Cu 2 O + Cu 2 S → 6Cu + SO2
107. The molecular shapes of SF4, CF4 and XeF4 are
1) different with 1, 0 and 2 lone pairs of electrons on the central atom, respectively
2) different with 0, 1 and 2 lone pairs of electrons on the central atom, respectively
3) the same with 1, 1 and 1 lone pair of electrons on the central atoms, respectively
4) the same with 2, 0 and 1 lone pairs of electrons on the central atom, respectively
Ans. (1)
In SF4,
m
n = 6 + 4 = 10
o
n
=5
.c
2
∴ Hybridization of sulphur is sp3d
e
Thus, shape is trigonal bipyramidal with one lone pair (See-saw shaped)
g
In CF4 ,
a
n=4+4=8
p
n
=4
e
2
e
∴ Hybridization of carbon is sp3
ie
Thus shape is tetrahedral with zero lone pair
In XeF4 ,
.a
n = 8 + 4 = 12
n
=6
w
2
∴ Hybridization of Xe is sp 3 d 2
w
Thus, shape is octahedral with 2 lone pairs (Square planar).
w
108. The disperse phase in colloidal iron (III) hydroxide and colloidal gold is positively and negatively charged, respectively.
Which of the following statements is NOT correct?
1) Coagulation in both sols can be brought about by electrophoresis
2) Mixing the sols has no effect
3) Sodium sulphate solution causes coagulation in both sols
4) Magnesium chloride solution coagulates, the gold sol more readily than the iron (III) hydroxide sol
Ans. (2)
By adding oppositely charged solution mutual coagulation of two sols can be done.
109. The number of hydrogen atom(s) attached to phosphorus atom in hypophosphorous acid is
1) three 2) one 3) two 4) zero
Ans. (3)
Molecular formula of the Acid is H 3 PO2
Structural formula is
O
P
H H
OH
110. What is the conjugate base of OH– ?
O 2– O–
2) 3) H 2O 4) O2
1)
m
Ans. (1)
o
OH ( − ) - H ( + ) = O 2-
.c
111. Heating an aqueous solution of aluminium chloride to dryness will give
1) Al (OH)Cl2 2) AL 2O 3 3) Al2Cl6 4) AlCl3
e
Ans. (3)
g
Aluminium chloride in aqueous solution exists as ions pair
a
[AlCl2 (H 2 O) 4 ]+ (aq) + [AlCl4 (H 2 O) 2 ]− (aq)
2AlCl3 + 6H 2 O
p
The crystallization of AlCl3 from aqueous solution therefore yields an ionic solid having composition
e
[AlCl2 (H 2 O) 6 ]+ [AlCl4 (H 2 O) 6 ]− which on heating gives Al 2 Cl 6 .
e
[AlCl 2 (H 2 O) 6 ]+ [AlCl 4 (H 2 O) 6 ]− 460→ Al 2 Cl 6 + 12H 2 O
K
ie
112. The correct order of the thermal stability of hydrogen halides (H - X) is
.a
1) HI > HCl < HF > HBr 2) HCl < HF > DBr < HI
3) HF > HCl > HBr > HI 3) HI > HBr > HCl > HF
w
Ans. 3)
Thermal stability is direictly proportional to bond dissociation energy and bond dissociation is inversely proportional
w
to bond length. The decreasing order of bond dissociation energy is HF > HCl > HBr > HI
∴ Order of thermal stability is HF > HCl > HBr > HI
w
113. Calomel (Hg2Cl2) on reaction with ammonium hydroxide gives
Hg2O 3) NH2 - Hg - Hg - Cl 4) HgNH2Cl
1) HgO 2)
Ans. (4)
Hg 2Cl 2 + 2 NH 3 → Hg ↓ Hg( NH 2 )Cl ↓ + NH 4Cl
Mercury(II) amido chloride
114. The number and type of bonds between two carbon atoms in calcium carbide are
1) Two sigma, two pi 2) Two sigma, one pi
3) One sigma, two pi 4) One sigma, one pi
Ans. (3)
C
Ca
C
115. The odixation state of chromium in the final product formed by the reaction between Kl and acidified potassium
dichromate solution is
1) +3 2) +2 3) +6 4) +4
Ans. (1)
Cr2 O 7 2 − + I (-) + H ( + ) → Cr 3+ + I 2 + H 2 O
116. In silicon dioxide
1) there are double bonds between silicon and oxygen atoms
2) silicon atom is bonded to two oxygen atoms
3) each silicon atom is surrounded by two oxygen atoms and each oxygen atom is bonded to two silicon
atoms.
4) each silicon atom is surrounded by four oxygen atoms and each oxygen atom is bonded to two silicon
atoms
Ans. (4)
m
Silicon dioxide exhibits polymorphism. It is a network solid in which each Si atom is surrounded tetrahedral by
four oxygen atoms.
o
117. The lanthanide contraction is responsible for the fact that
.c
1) Zr and Zn have the same oxidation state
2) Zr and Hf have about the same radius
e
3) Zr and Nb have similar oxidation state
g
4) Zr and Y have about the same radius
Ans. (2)
a
As a result of lanthanide contraction there is a close similarity in size. Zr and Hf have nearly same atomic radius
p
i.e. 160 and 158 pm respectively.
e
118. The IUPAC name of the coordination compound K3[Fe(CN)6] is
1) Tripotassium hexacyanoiron (II)
e
2) Potassium hexacyanoiron (II)
ie
3) Potassium hexacyanoferrate (III)
4) Potassium hexacyanoferrate (II)
.a
Ans. (3)
119. In which of the following arrangements the order is NOT according to the property indicated against it ?
w
1) Li < Na < K < Rb :
Increasing metallic radius
w
2) I < Br < F < Cl :
Increasing electron gain enthalpy
w
(with negative sign)
3) B < C < N < O :
Increasing first ionization enthalpy
4) Al3+ < Mg2+ < Na+ < F– :
Increasing ionic size
Ans. (3)
Ionization Enthalpy of Nitrogen is greater than that of Oxygen due to stable half filled configuration of Nitrozen.
120. Of the following sets which one does NOT contain isoelectronic species ?
BO3 − , CO3- , NO3 SO3 − , CO3 - , NO3
3 2 - 2 2 -
1) 2)
CN − , N 2 , C 2- PO4 − , SO 2- , ClO-
3
3) 4)
2 4 4
Ans. (2)


121. 2-Methylbutane on reacting with bromine in the presence of sunlight gives mainly
1) 1-bromo-3-methylbutane
2) 2-bromo-3-methylbutane
3) 2-bromo-2-methylbutane
4) 1-bromo-2-methylbutane
Ans. (3)
The reaction proceeds through free radical mechanism.
122. Which of the following compounds shows optical isomerism ?
[Co(CN ) 6 ]3− [Cr (C 2O4 ) 3 ]3−
2)
1)
[ZnCl4 ]2− [Cu ( NH 3 ) 4 ]2+
3) 4)
Ans. (2)
Due to lack of symmetry [Cr (C 2 O 4 ) 3 ]3− shows optical isomerism.
m
123. Which one of the following cyano complexes would exhibit the lowest value of paramagnetic behaviour?
o
[Co(CN ) 6 ]3− [ Fe(CN ) 6 ]3−
1) 2)
.c
[ Mn(CN ) 6 ]3− [Cr (CN ) 6 ]3−
3) 4)
e
(At. Nos : Cr = 24, Mn = 25, Fe = 26, Co = 27)
Ans. (1)
g
In [Co(CN ) 6 ]3− , Co is
a
in +3 state and has d6 configuration, the six
p
electrons get paired-up in presence of a strong filed ligand like CN(-)
e
124. The best reagent to convert pent-3-en-2-ol into pent-3-in-2-one is
1) Pyridinium chloro-chromate
e
2) Chromic anhydride in glacial acetic acid
ie
3) Acidic dichromate
4) Acidic permanganate
.a
ans. (1)
Pyridinium chloro-chromate oxidizes an alcoholic group selectively in the presence of carbon-carbon double bond.
w
24
Mg nucleus to form
125. A photon of hard gamma radiation knocks a proton out of 12
23
1) the isobar of
w
Na
11
23
2) the nuclide 11 Na
w
3) the isobar of parent nucleus
4) the isotope of parent nucleus
Ans. (2)
24 23
+1 p
12 Mg + γ →11 Na 1
126. Reaction of one molecule of HBr with one molecule of 1,3-butadiene at 400C gives predominantly
1) 1-bromo-2-butene under kinetically controlled conditions
2) 3-bromobutene under thermodynamically controlled conditions
3) 1-bromo-2-butene under thermodynamically controlled conditions
4) 3-bromobutene under kinetically controlled conditions
1, 4 addition
Ans. (3) CH 2 = CH − CH = CH 2 + HBr →
CH 3 − CH = CH − CH 2 − Br
1- bromo-2-Butene
127. The decreasing order of nucleophilicity among the nucleophiles
–
CH3C – O
a)
O
b) CH 3O –
c) CN –
O
–
S – O is
H 3C
d)
O
1) (c), (b), (a), (d) 2) (b), (c), (a), (d)
3) (d), (c), (b), (a) 4) (a), (b), (c), (d)
Ans. (2)
Q strong bases are generally good nucleophiles
m
128. Tertiary alkyl halides are practically inert to substitution by S N 2 mechanism because of
o
1) steric hindrance
.c
2) inductive effect
3) instability
e
4) insolubility
Ans. (1)
g
In S N 2 reaction mechanism reactivity of allkyl halide depends on stability of transition state which decreases with
a
steric hindrance in allkyl hallide.
p
129. In both DNA and RNA, heterocylic base and phosphate ester linkages are at -
e
C5 and C1' respectively of the sugar molecule
'
(1)
e
C1' and C5 respectively of the sugar molecule
'
2)
ie
' '
3) C 2 and C5 respectively of the sugar molecule
.a
' '
4) C5 and C 2 respectively of the sugar molecule
Ans. (2)
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130. Among the following acids which has the lowest pK a value ?
w
1) CH 3CH 2COOH
(CH3)2) CH – COOH
2)
w
3) HCOOH
CH 3COOH
4)
Ans. (3)
Strong acids have low value of pK a
131. Of the five isomeric hexanes, the isomer which can give two monochlorinated compounds is
1) 2-methylpentane 2) 2, 2-dimethylbutane
3) 2, 3-dimethylbutane 4) n-hexane
Ans. (3)
CH 3 CH 3
| |
CH 3 − CH − CH − CH 3
The molecule contains two types of hydrogens only.
Therefore can give two mono chlorinated compounds.
132. Alkyl halides react with dialkyl copper reagents to give
1) alkenyl halides
2) alkanes
3) alkyl copper halides
4) alkenes
Ans. (2)
2 R1 − x + R2Cu → R1 − R + CuX 2
(Corey - House synthesis)
133. Which one of the following methods is neither meant for the synthesis nor for separation of amines ?
1) Curtius reaction
2) Wurtz reaction
3) Hofmann method
m
4) Hinsberg method
o
Ans. (2) Wartz’s rxn gives alkanes.
.c
134. Which types of isomerism is shown by 2, 3- dichlorobutane ?
1) Structural
e
2) Geometric
g
3) Optical
a
4) Diastereo
Ans. (3)
p
The molecule has two chirality centres.
e
135. Amongst the following the most basic compound is
e
1) p-nitroaniline
ie
2) acetanilide
3) aniline
.a
4) benzylamine
Ans. (4)
w
Due to resonance of electron pair in aniline basic strength decreases. In benzylamine electron pair is not involve
in resonance.
w
NH 2 NH 2
CH 2NH 2 NHCOCH 3
w NO 2
(I) (II) (III) (IV)
Decreasing order of basic strength is (II) > (I) > (IV) > (III)
136. Acid catalyzed hydration of alkenes except ethene leads to the formation of
1) mixture of secondary and tertiary alcohols
2) mixture of primary and secondary alcohols.
3) secondary or tertiary alcohol
4) primary alcohol
Ans. (3)
Any alkene expect ethylene on acid catalyzed hydration gives secondary or tertiary alcohol because reaction
proceed according to electrophilic addition reaction mechanism.
137. Which of the following is fully fluorinated polymer?
1) PVC 2) Thiokol 3) Teflon 4) Neoprene
Ans. (3)
Thiokol
m
−CH 2 CH 2 − S − S − CH 2 CH 2 − S − S − CH 2CH 2 −
o
SS SS
n
.c
Neoprene :
−CH = C − CH = CH −
e
n
g
Cl
PVC:
a
HH
p
−C − C −
e
e
n
H Cl
ie
Teflon :
F F
.a
−C − C −
w
FF n
138. Elimination of bromine from 2-bromobutane results in the formation of -
w
1) predominantly 2-butyne
w
2) predominantly 1-butene
3) predominantly 2-butene
4) equimolar mixture of 1 and 2-butene
Ans. (3)
In elimination reaction of allkyl halide major product obtain according to Saytzef’s rule (highly substituted alkene
is the major product).
e lim ination
CH 3CH(Br)CH 2 CH 3    → CH 3CH = CHCH 3

− HBr
139. Equimolar solutions in the same solvent have
1) Different boiling and different freezing points
2) Same boiling and same freezing points
3) Same freezing point but different boiling point
4) Same boiling point but different freezing point
Ans. (2)
van’t Hoff factor (i) is not known so it is impossible to predict relation between colligative properties of equimolar
solutions in the same solvent.
If, i = 1
Then Equimolar solutions in the same solvent will have same boiling and same freezing points.
140. The reaction
O O
R–C
R–C + Nu +X
X Nu
is fastest when X is
1) OCOR 2) OC 2H 5 3) NH 2 4) Cl
Ans. (4)
m
Cl − is the best leaving group among the given option.
o
141. The structure of diborane (B2H6) contains
.c
1) four 2c-2e bonds and four 3c-2e bonds
2) two 2c-2e bonds and two 3c-3e bonds
e
3) two 2c-2e bonds and four 3c-2e bonds
g
4) four 2c-2e bonds and two 3c-2e bonds
Ans. (4)
a
Diborane, B 2 H 6 has hydrogen bridge structure B atoms and 4 terminal H atoms lie in the same plane; the terminal
p
B-H bonds may be regarded as conventional 2 centre-2 electron bonds i.e. 2c-2e bonds. The two bridging H
e
atoms lie symmetrically above and below this plane. Here three centers are united by two paired electrons
(3c-2e) bonding called banana bond.
e
142. Which of the following statements in relation to the hydrogen atom is correct?
ie
1) 3s, 3p and 3d orbitals all have the same energy
.a
2) 3s and 3p orbitals are of lower energy than 3d orbital
3) 3p orbital is lower in energy than 3d orbital
4) 3s orbital is lower in energy than 3p orbital
w
Ans. (1)
For hydrogen the energy order of orbital is
w
1s < 2s = 2p < 3s = 3p = 3d < 4s = 4p = 4d = 4f
w
143. Which of the following factors may be regarded as the main cause of lanthanide contraction?
1) Greater shielding of 5d electron by 4f electrons
2) Poorer shielding of 5d electrons by 4f electrons
3) Effective shielding of one of 4f electrons by another in the subshell
4) Poor shielding of one of 4f electron by another in the subshell
Ans. (4)
144. The value of the ‘spin only’ magnetic moment for one of the following configurations is 2.84 BM. The correct one
is
d5 (in strong ligand field)
1)
d3 (in weak as well as in strong fields)
2)
d4 (in weak ligand field)
3)
d4 (in strong ligand field)
4)
Ans. (4)
d4 in presence of strong field ligand, contains two unpaired electrons
145. Reaction of cyclohexanone with dimethylamine in the presence of catalytic amount of an acid froms a compound
if water during the reaction is continuously removed. The compound formed in generally known as
1) an amine 2) an imine
3) an enamine 4) a Schiff’s base
Ans. (3)
O N(CH3)2
O + HN (CH3)2
146. 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
m
acid is
o
CH3 CH3
.c
CH2COOH
e
2)
1) CH2COOH
g
OH OH
a
CH3 CH3
p CH(OH)COOH
e
e
3) 4)
CH(OH)COOH
ie
OH
OH
Ans. (3)
.a
CH3 CH3 CH3
(-)
OH i) HON
w
+ CHCl3 (+)
ii) H3O
w
CHO CH(OH) COOH
OH OH OH
w
147. If the bond dissociation energies of XY, X2 and Y2, (all diatomic molecules) are in the ratio of 1:1:0.5 and ∆ f H
for the formation of XY is -200 kJ mole–1. The bond dissociation energy of X2 will be
2) 300 kJ mol–1 3) 200 kJ mol–1 4) 100 kJ mol–1
1) 400 kJ mol–1
Ans. No correct option
148. 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
1) 0.11 2) 0.17 3) 0.18 4) 0.30
Ans. (1)
NH 3 (g) + H 2S(g)
NH 4 HS(s)
0
Initial 0 0.5
press.
0.5 + p
At equi. 0 p
0.5 + 2p = 0.84
∴ p = 0.17 atm
K p = p NH3 × p H 2S
= (0.67) × (0.17)
= 0.11 atm 2
149. 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 alongwith a solid residue. The solid residue give violet colour with alkaline
m
copper sulphate solution. The compound is
o
2)
1) CH 3CH 2 CONH 2 (NH 2 ) 2 CO
.c
3) 4)
CH 3CONH 2 CH 3 NCO
Ans. (2)
e
g
Re lative no. of atoms Simplest ratio
Element Percentage
a
1
1.67
20
C
p
6.67 4
H 6.67
e
3.33 2
46.67
N
e
1.67 1
26.66
O
ie
The molecular formula is CH 4 N 2 O
.a
So, the compound is H 2 NCONH 2
2 NH 2CONH 2 ∆ NH 2CONHCONH 2 + NH 3 ↑
→
w
Biuret
Biuret gives violet colour with alkaline copper sulphate solution
w
t1 3
150. can be taken as the time taken for the concentration of a reactant to drop to of its initial value. If the rate
4
w
4
t1
can be written as
constant for a first order reaction is K, the
4
1) 0.75 / K 2) 0.69 / K
3) 0.29 / K 4) 0.10 / K
Ans. (3)
2.303 4
t1/ 4 = log
K 3
0.29
=
K