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Model Paper of Paper-II- CSIR-UGC NET (Chemistry).


Posted Date: 22-Sep-2009  Last Updated:   Category: Entrance Exams    
Author: Member Level: Gold    Points: 2






Chemical Sciences
Paper II
1. (a) What is Zeise's salt? Show its structure and describe the bonding. (5)
(b) Use Coulomb's law to deduce the dimension of charge. (5)
(c) Explain which of the following is primarily responsible for the difference in
chemical properties of nanomaterials from the bulk. (2)
i. lattice defects
ii. surface to volume ratio
iii. London forces
(d) Suggest a synthetic method (may need more than one step) for the following
transformation.
(5)
MeO MeO
(e) Match the following: (3)
Compounds Type
1. progesterone i. antiulcer compound
2. amoxycillin ii. antiallergic
3. morphine iii. antibacterial
iv. hallucinogen
v. harmone
2. (a) Identify the products A to E in the following reactions.
(9)
(i) W(CO)6 + LiPh ? A
Me3O+BF4
-
B
Cl
Cl
(ii) + Fe2(CO)9 C
(iii) [Ph3C3][X] + Ni(CO)4 ? D
(iv) (?5-Cp)2Fe + CH3COCl ? E
(b) Draw the structures of Co4(CO)12 and Ir4(CO)12.
(6)
3. (a) Write appropriate equations for the synthesis of (i) N3P3Cl6 and (ii)
N3P3F6.
(4)
(b) Sketch the 31P NMR spectral pattern for the following compound
[consider only 2J(PP)].
(5)
N
P
N
P
N
P
Cl Cl
Cl
Cl
SPh
SPh
(c) Sketch all isomers of PF3(CH3)2 assuming a trigonal bipyramidal
geometry in each case.
(6)
4. (a) What is the origin of the blue colour in Prussian Blue? Comment on
the effect of (i) oxidant and (ii) reductant on its colour.
(7)
(b) Give an example of a diamagnetic transition metal hydride complex.
How is the presence of metal bound hydride detected by
spectroscopic methods.
(6)
(c) Rh(PPh3)3Cl A
THF, H2
Draw the structure of A above, showing the stereochemistry.
(2)
5. (a) The complex ion [Co(tren)NH3Cl]2+ (tren = N(CH2CH2NH2)3) exists as
red and purple isomers. Draw the structures of these two forms.
(4)
(b) Red isomer undergoes hydrolysis much more rapidly compared to
the purple one. Explain.
(3)
(c) Match the items in Column I with those in Column II.
(8)
6. (a) Sketch the structure of the bis(dimethylglyoximato)nickel(II) complex
used in the gravimetric estimation of nickel(II). Why is a large excess of
dimethyglyoxime solution avoided in this estimation?
(7)
(b) Two isomers of [PtCl2(PEt3)2] have 1J(195Pt-P) values of 3500 Hz and
2400 Hz respectively. Assign the coupling constants to the isomers,
giving reason.
(4)
Column I Column II
A. Siderophores 1. Co
B. Chlorophyll 2. Fe
C. Superoxide dismutase 3. Mg
D. Vitamin B12 4. Cu-Zn
(c) 23
11Na is a stable nucleus. Predict which of the following unstable
nuclei decay by ß– or ß+ emission.
(i) 23
10Ne (ii) 23
12Mg (iii) 22
11Na (iv) 24
11Na
(4)
7. (a) Write equations for reduction of oxygen at dropping mercury electrode,
when the medium is alkaline.
(4)
(b) Sketch the curve for amperometric titration of 0.01M Pb(NO3)2 with
0.05 M K2Cr2O7 at –1.0V (vs SCE), the potential at which both the
species are electroactive.
(4)
(c) Match items in column I with those of II.
(7)
I II
A. Supporting electrolyte 1. Derivative Thermogravimetry
B. Ilkovic equation 2. Differential Scanning Calorimetry
C. dm
dt
3. Quantum yield
D. dH
dt
4. Migration current
E. Spectrofluorimetry 5. Diffusion current
F. Atomic Absorption Spectrophotometry 6. Mercury
G. Cold vapour technique 7. Graphite furnace
8. (a) Write equations for the preparation of:
(i) S4N4 from SCl2(liq.)
(ii) P4S10 from white phosphorus
(4)
(b) Sketch the structures of S4N4 and P4S10
(4)
(c) A one-electron paramagnetic copper complex can have two charge
distributions:-
CuII–L or CuI –L•? (L= organic ligand)
How they can be distinguished by ESR spectroscopy?
(7)
9. (a) Draw generally accepted structure of active site of the enzyme
involved in nitrogen fixation. Indicate the site on which nitrogen first
binds.
(6)
(b) Bent metallocenes have general formulation [(?5-C5H5)2MLX]. Write
two examples choosing appropriate 'M', having different values of 'x'.
(6)
(c) Examples of carbonylate anions are many more than those of metal
carbonyl cations. Explain.
(3)
10. (a) KMnO4 shows an intense pink colour, while KReO4 is colourless.
Explain.
(5)
(b) Copper(I) iodide is a stable species, while coppe(II) iodide does not
exist. Explain.
(6)
(c) H+ is a hard acid while H – is a soft base. Explain.
(4)
11. (a) Identify A – D in the following catalytic cycle with their structures
(8)
Rh
Cl PPh3
Ph3P PPh3
H2 [ A ] -PPh3 [ B ]
[ C ]
hydride
migration
[ D ] -PPh3 R
R
(b) Draw the molecular structures of the following compounds in solid state
(i) Ti(?1-Cp)2(?5-Cp)2 (ii) U(?5-Cp)4 (iii) Sm(?5-Cp*)3
(7)
12. (a) What property/properties of lanthanide ß-diketonate complex make(s)
them useful as shift reagents in NMR spectroscopy?
(3)
(b) Write the products in the following reactions.
(i) 2 5
I O ?C?O?
(ii) HgO
2 Cl ????
(iii) SO2 +H2SO4
3 NaClO ?????
(iv) 2%NaOH Solution
2 F ???????
(8)
(c) 10B used in nuclear reactors participates in two reactions. One reaction
yields 7Li and another product X. The other reaction yields 3T and X.
Identify X and write two balanced nuclear reactions.
(4)
13. (a) For the complexation reaction
[Ni(en)2(H2O)2]2+ (aq) + tren (aq) ?? [Ni(tren)(H2O)2]2+(aq) + 2en (aq)
(A)
the log ß value is 1.88. Explain this value giving structure of A.
[tren = N(CH2CH2NH2)3]
(5)
(b) What change in the position of iron in hemoglobin occurs upon
binding to oxygen and why?
(4)
(c) Identify isolobal pairs from the following
CH3, CH2, CH, Cr(CO)4, Mn(CO)5, and Co(CO)3
(6)
14. a) The spacing between the first and second lines in the rotational spectrum of a
diatomic molecule with an equilibrium bond length of 1 Å is 40 cm-1. The spacing
between the 9th and 10th lines is 36 cm-1. Calculate the extension of the bond due
to the centrifugal distortion.
(7)
b) Calculate the vibrational quantum number at the dissociation limit for a
diatomic molecule (given the anharmonicity constant as 0.05).
(8)
15. a) The character table of the point group D3 is given below:
D3 E 2C3 3C2
A1 1 1 1
A2 1 1 -1 z
E 2 -1 0 (x,y)
Show that the row A2 is orthogonal to the row E.
(4)
b) Given the reducible representation, G, in D3
E 2C3 3C2
G 7 1 1
Determine its irreducible components.
(5)
c) Use the above character table to determine whether the A1 ? A2 transition is
allowed when the change in transition moment is (i) along z – axis and (ii) in
the x-y plane.
(6)
16. a) Show that all Bragg reflections of a primitive cubic crystal have the same
intensity.
(7)
b) Plot the Fermi factor f(E) versus energy, E, for a free electron metal at T = 0 K
and T > 0 K.
(4)
c) The temperature variation of the high-temperature magnetic susceptibility, ?,
of three solids is shown below. Identify the ferromagnet, paramagnet and
antiferromagnet.
T
?-1
(4)
17. a) For a particle in a one-dimensional (x) box of length a, where the potential is
given by
V (x) = 8 x < 0, x > a
V (x) = 0 0 = x = a
write the wavefunctions (without derivation) for all states for the full region of x.
State if the wavefunctions are even or odd (i.e. have parity symmetry). State the
boundary conditions involved in the derivation.
(4+1+3)
b) Discuss the parity of the wavefunctions if, in the above problem, the origin is
shifted to the centre of the box, i.e. the potential V (x) is
V (x) = 8 x < – a/2, x > a/2
V (x) = 0 - a/2 = x = a/2
Write the wavefunctions in this case.
(7)
18. a) Find the inverse of the matrix 1 0
0 2
? ?
? ?
? ?
(8)
b) How do the states ? , ? *, -i? , and eia? differ with respect to observable
properties and why?
(7)
19. a) Show that x = 0 for systems that respect parity as a constant of
motion.
(6)
b) Evaluate the commutator [ ] x z L2 , L .
(9)
20. a) Two variables xi and yi are related by yi = 3 – 2 xi. Show that the covariance of
x and y, defined by c(x, y) = xy - x y , is equal to
-2? x2 , where ? x2 = x2 - x 2 .
(10)
b) For a polydisperse polymer solution, use basic definitions to show that w M =
n
2n
M M .
(5)
21. a) Calculate the mean ionic activity coefficient of 0.01 mol L-1 NaCl aqueous
solution at 298 K (A = 0.509 for an aqueous solution at 298 K).
(8)
b) Write the cell reactions and predict whether it is spontaneous or nonspontaneous
in a cell at 298 K.
Cd(s)?Cd2+(aq)?? Fe2+(aq)?Fe(s)
Given: E0(Cd2+/Cd) = -0.403 V and
E0(Fe2+/ Fe) = -0.447 V
(7)
22. a) For a second order reaction 2A ? P, show that t½ [ ]0 ?1 A where t½ is the
half-life and [A]0 is the initial concentration.
(10)
b) The equilibrium constant (K) for the elementary reaction at 1000 K
C2H6(g) 2
CH3(g) is 1.30 ×
10-13 mol L-1
and the rate constant for the
forward reaction (k1) is 1.57 × 10-3 s-1. Write the rate law and calculate the
rate constant for the reverse reaction (k-1)
(5)
a
c
b
P
V
23. a) 3.64 g of compound A (molar mass 150) is dissolved in 180 g of benzene and
the vapour pressure of this solution is 756 torr at the boiling point of benzene.
Calculate the molar mass of A in benzene and explain the discrepancy, if any
[assume dilute solution].
(8)
b) First two quantum states of an atom A (3P0 and 3P1) are separated by 300 cm-1.
Calculate the electronic partition function at 1000 K for this system (h/1000kb
= 4.8 × 10-14 s).
(7)
24. a) Calculate the entropy of mixing and Gibbs free energy of mixing of 5 moles of
component A and 5 moles of component B at 27 °C.
(10)
b) Show that, if an engine takes up heat Q from a sink at a temperature T2 and
gives to a source at a temperature T1 without any work, the process would
violate the principle ? S(universe) = 0.
(5)
25. a) During an adiabatic reversible expansion (a ? b), 1 mole of a monatomic ideal
gas undergoes a decrease of temperature from 400 K to 100 K. If the initial
volume is 32.8 L, calculate the final volume.
(4)
b) Transformation a ? b can also be achieved by undergoing (i) an isothermal
reversible expansion (a ? c) and (ii) an isochoric reversible process (c ? b).
Calculate the entropy change in each process and the total entropy change in
going from a ? b.
(5+5+1)
26 (a) Draw a correlation diagram for disrotatory opening of a cyclobutene to
buta-1,3-diene. Predict the outcome of the reaction in the ground state.
(10)
(b) Predict the products A and B in the following reactions, and suggest
mechanism of their formation.
(5)
? h?
[ A ] [ B ]
27 (a) Predict the products A and B (with correct stereochemistry) in the following
reaction, and suggest a mechanism of formation of B.
(6)
O
OAc
+
h?
[ A ] aq. KOH
[ B ]
(b) Triplet sensitized irradiation of compound C gives D. Suggest a
mechanism.
(6)
O
h?
sensitizer
O
[ C ] [ D ]
(c) Suggest a plausible mechanism for the following transformation.
(3)
O h?
OH
H
28 (a) In the following transformation, predict the structures (with appropriate
stereochemistry) of compounds A and B.
(6)
Me CHO
OMe
R MeMgBr
[ A ]
NaH
MeI
[ B ]
(b) Explain the origin of stereoselectivity in the formation of A with Cram
chelate or Felkin-Anh model.
(4)
(c) Predict the absolute configuration of the newly formed stereocentre and
state whether the compound B will be optically active or not.
(5)
29 (a) Write the structures of the compounds A-C and the reagent D in the
reaction sequence given below.
(10)
N
H
HNMe2 [ A ]
AcOH
[ B ]
Me2SO4 NaCN [ C ]
N
H
[ D ] NH2
HCHO
(b) Write the structures of the products E-G, and write the name of the
dipeptide G.
(5)
H2N COOH (tBuOCO)2O
[ E ]
DCC
COOCH2Ph
NH2
[ F ] [ G ]
aq. HBr
30 (a) The kH/kD of base catalysed elimination reaction given below in H2O and D2O
was found to be 0.13. Write suitable mechanism consistent with this
observation.
(5)
O2N
NMe3
O2N
H2O or D2O
base
(b) D-Glucose is converted to unsaturated sugar as given below. Write the
structures of A-C.
(6)
O
HO
HO
HO
HO OH
[ A ]
Ac2O, py
[ B ] Zn [ C ]
AcOH
O
AcO
AcO
O
Ph
PhCH2OH
BF3.Et2O
PBr3
H2O
(c) Write the structures of D and E in the sequence given below.
(4)
[ D ] [ E ]
BH2 CO, H2O
H2O2, NaOH
OH
NaBH4
31 Identify A-G (with appropriate stereochemistry) in the following synthetic
sequences. (15)
[ A ] [ B ]
[ C ]
[ D ]
CHO
MgBr
MnO2
O Ph
m-CPBA
NaHCO3
[ E ] [ F ] [ G ]
MeO
O
O
O
AlCl3 +
Zn-Hg
HCl
H2SO4
32 (a) Write the structure of the compounds A and C, and suggest suitable
mechanism for their conversion to the products B and D, respectively.
(10)
O NH2OH
[ A ] H2SO4 CN
[ B ]
O
H2O2 [ C ]
OH
NH2NH2
NaOH KOH
[ D ]
(b) Suggest suitable reagents for the following selective transformations.
(5)
Ph O HO
CHO Me
(i)
(ii)
33 (a) Identify the products A to C in the following reaction sequence. (6)
[ B ]
i NaNH2
ii HCHO
[ A ]
LiAlH4
H3O+ [ C ]
(-)-DET
Ti(OiPr)4
tBuOOH
(b) Suggest a mechanism for the following transformation. (4)
PTSA
(c) Suggest a suitable synthetic sequence for the following transformation.
(5)
O
O
O
O
34 (a) Identify the products A to D in the following reaction sequence (10)
OH
CHCl3
NaOH
[ A ]
NaH
[ B ]
Br Me
Ph3P=CHCOOEt
[ C ]
?
[ D ]
(b) Identify the compound E and suggest a suitable mechanism for its conversion to
compound F.
(5)
h?
[ E ]
i SOCl2
ii CH2N2
COOH
CH2Cl2
O
[ F ]
35 (a) Write the structures of the two possible products A and B in the
reaction given below, and give suitable mechanism of their formation.
Suggest how 1H NMR spectrum can be used to differentiate A and B.
(10)
[ A ]
O
+ [ B ]
m-CPBA
(b) How would you distinguish 2-methylbutanal and 3-methylbutanal
using mass spectrometry.
(5)
36 (a) The monoterpene citral undergoes reactions given below. Write the
structures of the products A-F. (9)
CHO
citral
[ A ]
Tollen's reagent
[ B ]
KHSO4 aq. K2CO3 [ C ] + MeCHO
(C10H16O2)
(C10H14) (C8H14O)
[ D ] [ E ] [ F ]
KMnO4
(C5H8O3) (C3H6O) (C2H2O4)
+ +
(b) Identify the products G to I in the synthesis of cocaine (6)
CHO
CHO
+ MeNH2 + HO OEt
O O O KOH
[ G ]
?
[ H ]
i. Na-Hg
ii. H3O+
[ I ]
i. HCl, MeOH
ii. PhCOCl, py
NMe
COOMe
OCOPh
cocaine
37 Deduce the structure of the organic compound having the following
analytical and spectral data.
Analysis C, 74.98; H, 6.86
Mass 176, 131 (base peak), 103, 77.
IR ?max 1714, 1639 cm-1
1H NMR d 1.31 (t, 3 H, J=7.1 Hz), 4.2 (q, 2 H, J=7.1 Hz), 6.43 (d, 1 H,
J=15.8 Hz), 7.24-7.57 (m, 5 H), 7.67 (d, 1 H, J=15.8 Hz).
13C NMR d 14.3, 60.4, 118.4, 128.1, 128.9, 130.2, 134.5, 144.5, 166.8.
(15)


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