JEE MAIN - Chemistry (2006)

1
The standard enthalpy of formation $$\Delta _fH^o$$ at 298 K for methane, CH₄(g), is –74.8 kJ mol^–1. The additional information required to determine the average energy for C – H bond formation would be :
Trả lời
(A)
the dissociation energy of H₂ and enthalpy of sublimation of carbon
2
An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If T_i is the initial temperature and T_f is the final temperature, which of the following statements is correct?
Trả lời
(A)
(T_f)_irrev > (T_f)_rev
3
The enthalpy changes for the following processes are listed below :

Cl₂(g) = 2Cl(g), 242.3 kJ mol^–1
I₂(g) = 2I(g), 151.0 kJ mol^–1
ICl(g) = I(g) + Cl(g), 211.3 kJ mol^–1
I₂(s) = I₂(g), 62.76 kJ mol^–1

Given that the standard states for iodine and chlorine are I₂(s) and Cl₂(g), the standard enthalpy of formation for ICl(g) is :
Trả lời
(C)
+16.8 kJ mol^–1
4
($$\Delta H - \Delta U$$) for the formation of carbon monoxide (CO) from its elements at 298 K is : (R = 8.314 J K^–1 mol^–1)
Trả lời
(B)
1238.78 J mol^–1
5
Phosphorus pentachloride dissociates as follows, in a closed reaction vessel
PCl₅ (g) $$\leftrightharpoons$$ PCl₃ (g) + Cl₂ (g)
If total pressure at equilibrium of the reaction mixture is P and degree of dissociation of PCl₅ is x, the partial pressure of PCl₃ will be
Trả lời
(A)
$$\left( {{x \over {x + 1}}} \right)P$$
6
The equilibrium constant for the reaction
SO₃ (g) $$\leftrightharpoons$$ SO₂ (g) + $$1 \over 2$$ O₂ (g)
is K_c = 4.9 $$\times$$ 10^–2. The value of K_c for the reaction
2SO₂ (g) + O₂ (g) $$\leftrightharpoons$$ 2SO₃ (g) will be :
Trả lời
(A)
416
7
Given the data at 25^oC,
Ag + I^- $$\to$$ AgI + e^- , E^o = 0.152 V
Ag $$\to$$ Ag⁺ + e^-, E^o = -0.800 V
What is the value of log K_sp for AgI? (2.303 RT/F = 0.059 V)
Trả lời
(D)
–16.13
8
CH₃Br + Nu^- $$\to$$ CH₃ - Nu + Br^- The decreasing order of the rate of the above reaction with nucleophiles (Nu^–) A to D is
[Nu^– = (A) PhO^–, (B) AcO^–, (C) HO–, (D) CH₃O^–]
Trả lời
(C)
D > C > A > B
9
The increasing order of stability of the following free radicals is
Trả lời
(B)
$${(C{H_3})_2}\mathop C\limits^ \bullet H$$ < $${(C{H_3})_3}\mathop C\limits^ \bullet $$ < $${({C_6}{H_5})_2}\mathop C\limits^ \bullet H$$ < $${({C_6}{H_5})_3}\mathop C\limits^ \bullet$$
10
Increasing order of stability among the three main conformations (i.e. Eclipse, Anti, Gauche) of 2-fluoroethanol is
Trả lời
(C)
Eclipse, Anti, Gauche
11
CH₃Br + Nu^- $$\to$$ CH₃ - Nu + Br^- The decreasing order of the rate of the above reaction with nucleophiles (Nu^–) A to D is
[Nu^– = (A) PhO^–, (B) AcO^–, (C) HO–, (D) CH₃O^–]
Trả lời
(C)
D > C > A > B
12
How many EDTA (ethylenediaminetetraacetic acid) molecules are required to make an octahedral complex with a Ca²⁺ ion?
Trả lời
(C)
One
13
Phenyl magnesium bromide reacts with methanol to give
Trả lời
(B)
a mixture of benzene and Mg(OMe)Br
14
Fluorobenzene (C₆H₅F) can be synthesized in the laboratory
Trả lời
(B)
from aniline by diazotisation followed by heating the diazonium salt with HBF₄
15
Reaction of trans-2-phenyl-1-bromocyclopentane on reaction with alcoholic KOH produces
Trả lời
(D)
3-phenylcyclopentene
16
HBr reacts with CH₂ = CH – OCH₃ under anhydrous conditions at room temperature to give
Trả lời
(D)
H₃C – CHBr – OCH₃
17
The term anomers of glucose refers to
Trả lời
(D)
isomers of glucose that differ in configuration at carbon one (C-1)
18
The pyrimidine bases present in DNA are
Trả lời
(C)
cytosine and thymine
19
In Fe(CO)₅, the Fe – C bond possesses :
Trả lời
(B)
both $$\sigma$$ and π characters
20
The $$IUPAC$$ name of the compound shown below is :

Trả lời
(A)
$$3$$-bromo - $$1$$-chlorocyclohexene
21

The alkene formed as a major product in the above elimination reaction is
Trả lời
(B)
22
The structure of the major product formed in the following reaction

is
Trả lời
(B)
23
The structure of the compound that gives a tribromo derivative on treatment with bromine water is
Trả lời
(C)
24

The electrophile involved in the above reaction is
Trả lời
(D)
25
Among the following the one that gives positives iodoform test upon reaction with $${I_2}$$ and $$NaOH$$ is
Trả lời
(B)
$$PhCHOHC{H_3}$$
26
The correct order of increasing acid strength of the compounds

Trả lời
(A)
$$D < A < B < C$$
27
A metal, $$M$$ forms chlorides in its $$+2$$ and $$+4$$ oxidation states. Which of the following statements about these chlorides is correct?
Trả lời
(A)
$$MC{l_2}$$ is more ionic than $$MC{l_4}$$
28
Rate of a reaction can be expressed by Arrhenius equation as:
$$$k = A\,{e^{ - E/RT}}$$$ In this equation, E represents
Trả lời
(A)
the energy above which all the colliding molecules will react
29
Among the following mixtures, dipole-dipole as the major interaction, is present in
Trả lời
(B)
acetonitrile and acetone
30
18 g of glucose (C₆H₁₂O₆) is added to 178.2 g of water. The vapour pressure of water for this aqueous solution at 100^oC is
Trả lời
(D)
752.40 Torr
31
The molar conductivities $$ \wedge _{NaOAc}^o$$ and $$ \wedge _{HCl}^o$$ and at infinite dilution in water at 25^oC are 91.0 and 426.2 Scm²/mol respectively. To calculate $$ \wedge _{HOAc}^o$$ , the additional value required is
Trả lời
(D)
$$ \wedge _{NaCl}^o$$
32
Which of the following chemical reactions depicts the oxidizing behaviour of H₂SO₄?
Trả lời
(C)
2HI + H₂SO₄ $$\to$$ I₂ + SO₂ + 2H₂O
33
Resistance of a conductivity cell filled with a solution of an electrolyte of concentration 0.1 M is 100$$\Omega $$. The conductivity of this solution is 1.29 S m^–1. Resistance of the same cell when filled with 0.2 M of the same solution is 520 $$\Omega $$, The molar conductivity of 0.02 M solution of the electrolyte will be
Trả lời
(D)
12.4 $$\times$$ 10^–4 S m² mol^–1
34
A reaction was found to be second order with respect to the concentration of carbon monoxide. If the concentration of carbon monoxide is doubled, with everything else kept the same, the rate of reaction will
Trả lời
(C)
increase by a factor of 4
35
In the transformation of $${}_{92}^{238}U$$ to $${}_{92}^{234}U$$, if one emission is an α-particle, what should be the other emission(s)?
Trả lời
(A)
Two $$\beta^-$$
36
The following mechanism has been proposed for the reaction of NO with Br₂ to form NOBr:
NO(g) + Br₂ (g) $$\leftrightharpoons$$ NOBr₂ (g)
NOBr₂ (g) + NO (g) $$\to$$ 2NOBr (g)
If the second step is the rate determining step, the order of the reaction with respect to NO(g) is
Trả lời
(D)
2
37
The increasing order of the first ionization enthalpies of the elements B, P, S and F (lowest first) is :
Trả lời
(D)
B < S < P < F
38
Which of the following statements is true?
Trả lời
(D)
HNO₃ is a stronger acid than HNO₂
39
The “spin-only” magnetic moment [in units of Bohr magneton, (µ_B)] of Ni²⁺ in aqueous solution would be : (Atomic number of Ni = 28)
Trả lời
(A)
2.84
40
Lanthanoid contraction is caused due to :
Trả lời
(D)
the imperfect shielding on outer electrons by 4f electrons from the nuclear charge
41
Nickel (Z = 28) combines with a uninegative monodentate ligand X^– to form a paramagnetic complex [NiX₄]²⁻ . The number of unpaired electron(s) in the nickel and geometry of this complex ion are, respectively
Trả lời
(B)
two, tetrahedral
42
How many moles of magnesium phosphate Mg₃(PO₄)₂ will contain 0.25 mole of oxygen atoms?
Trả lời
(D)
3.125 $$\times$$ 10^-2
43
Density of a 2.05M solution of acetic acid in water is 1.02 g/mL The molality of the solution is
Trả lời
(A)
2.28 mol kg^-1
44
Uncertainty in the position of an electron (mass = 9.1 $$\times$$ 10^-31 kg) moving with a velocity 300 ms^-1, accurate upto 0.001% will be (h = 6.63 $$\times$$ 10^-34 Js)
Trả lời
(A)
1.92 $$\times$$ 10^-2 m
45
Uncertainty in the position of an electron (mass = 9.1 $$\times$$ 10^-31 kg) moving with a velocity 300 ms^-1, accurate upto 0.001% will be (h = 6.63 $$\times$$ 10^-34 Js)
Trả lời
(A)
1.92 $$\times$$ 10^-2 m
46
According to Bohr's theory, the angular momentum of an electron in 5^th orbit is
Trả lời
(B)
2.5 $$h/\pi$$
47
Which of the following sets of ions represents a collection of isoelectronic species?
Trả lời
(C)
K⁺, Cl^-, Ca²⁺, Sc³⁺
48
Following statements regarding the periodic trends of chemical reactivity of the alkali metals and the halogens are given. Which of these statements gives the correct picture?
Trả lời
(D)
In alkali metals the reactivity increases but in the halogens it decreases with increase in atomic number down the group
49
Which of the following molecules/ions does not contain unpaired electrons?
Trả lời
(A)
$$O_2^{2−} $$
50
In which of the following molecules/ions are all the bonds not equal?
Trả lời
(C)
SF₄
51
The decreasing values of bond angles from NH₃ (106^o) to SbH₃ (91^o ) down group-15 of the periodic table is due to
Trả lời
(C)
decreasing lp-bp repulsion