CLASS: M.Sc. CHEMISTRY
15N/367
St. JOSEPH’S COLLEGE (AUTONOMOUS) TIRUCHIRAPPALLI – 620 002
SEMESTER EXAMINATIONS – NOVEMBER 2015
TIME: 40 Minutes.
MAXIMUM MARKS: 30
SEM
SET
PAPER CODE
TITLE OF THE PAPER
I
2015
14 PCH 1102
ORGANIC CHEMISTRY - I
SECTION - A
Answer all the questions:
Choose the correct answer:
1.
What do you understand by the 3D pictorial representations of the
wave functions of the electrons?
a)
c)
2.
3.
4.
5.
30 X 1 = 30
orbitals
eigen values
b)
d)
eigen functions
both A & B
Identify the propable shape of the 3dz2 orbital.
a)
b)
c)
d)
none
Identify the hybridization and geometry at the carbonyl group in
acetone.
a) sp2, tetrahedral
b) sp2, linear
c) sp2, trigonal planar
d) sp3, square pyramidal
Identify the most polar molecule in the given list.
a) Ph-OH
b) Ph-NO2 c) p-C6H4Cl2 d) C6H5Br
Choose the correct order of decreasing strength of +I groups.
a) O- > COO- > CR3 > CH2R > CH3
b) NR3+ > SR2+ > NH3+> NO2 > SO2R
c) COOH > F > Cl > Br > OAr
d) O- < COO- < CR3 < CH2R < CH3
6.
7.
8.
9.
10.
11.
12.
13.
14.
What term does signify the instantaneous-dipole-induced-dipole
interactions operating between non-polar molecules?
a) Hydrogen bonding
b) dipole-dipole interaction
c) van der Waals interactions
d) all the three A, B & C
Identify the isomerism exhibited by the given compound –
CH3CH=C(Br)CH2CH3 (3-bromopent-2-ene)
a) Z-E isomerism
b) cis-trans isomerism
c) optical isomerism
d) none
How many stereoisomers are possible to exist for aldotetrose?
a) 9
b) 10
c) 8
d) 4
What do you understand by the term 'diastereomers'?
a) non-superimposable mirror-image isomers
b) non-superimposable non-mirror-image isomers
c) superimposable mirror-image isomers
d) none
What is not true about axial chirality?
a) Two pairs of vertices in the elongatedtetrahedron
b) absence Cn, i, s, Sn symmetry
c) asymmetric carbon
d) chiral axis
What kind of chirality is shown by the 'ansa' compounds?
a) carbon chirality
b) axial chirality
c) planar chirality
d) all the three A, B & C
Which of the following is true about (S)-enantiomer?
a) it rotates the plane of polarized light to the right
b) it rotates the plane of polarized light to the left
c) it's the mirror-image of the corresponding R-enantiomer
d) it has the highest priority order group on the left
The Huckel’s 4n+2 rule is applicable to
a) alicyclic compounds
b) aromatic compounds
c) cyclic compounds
d) polycyclic compounds
Which of the following is the same as the tropylium ion?
a) cyclopropenyl anion
b) cyclopentadienyl cation
c) cycloheptatrienyl anion
d) cycloheptatrienyl cation
15.
16.
17.
18.
19.
20.
21.
22.
23.
How many spin states do exist for the carbene intermediate
a) singlet
b) triplet c) doublet d) both A and B
Pinacol-pinacolone rearrangement takes place through the
formation of the intermediate
a) carbaninon b) carbocation c) carbene d) nitrene
How many resonance structures are there for naphthalene other
than the Dewar's structures?
a) 5
b) 4
c) 3
d) 2
The order of stability of carbonimu ion is
a) Secondary > tertiary > primary
b) Primary> secondary > tertiary
c) Tertiary > secondary > primary
d) None of these
In a homolytic bond fission, which of the following is formed?
a) carbonium ion
b) carbanion
c) free-radical
d) none
Exchange of an atom in the substrate for one of its heavier isotope
leads to
a) decrease in rate
b) increase in rate
c) iostope effect
d) both A & C
The rate of a overall reaction is determined by the rate of
a) fast step
b) slow step
c) equilibrium step
d) none
In an organic reaction, the leaving group goes with an unshared
pair of electrons is called
a) nucleofuge
b) nucleophile
c) electrofuge
d) electrophile
What is the impact of anchimeric assistance on the rate of a
reaction?
a) rate, enhanced
b) rate, retarded
c) product yield, enhanced
d) none
24.
25.
26.
27.
28.
29.
30.
A reaction will be ______ if the energy of the products is less than
the energy of the reactants.
a) endothermic
b) exothermic
c) isothermic
d) none
Identify the type of reaction, given: R-X + Z: ------> R-Z + Xa) nucleophilic substitution
b) electrophilic substitution
c) diradical substitution
d) none
We have a set of substrates and nucleophiles:
a. RI b. RNMe3+ c. OH- d. NMe3 e. H2S
predict the possible combinations of reactions
a) a + c, a + d, b + c, b + e
b) a + c, a + e, b + c, b + c
c) a + e, a + d, b + c, b + e
d) a + c, a + e, b + c, b + d
Identify the exact stereochemical implication of the given
reaction.(+)-malic acid + SOCl2 ------> (+)-chlorosuccinic acid
a) SNi reaction
b) retention of configuration
c) internal nucleophile
d) all the three A, B & C
Why does norbornenyl tosylate substrate reacts faster than the
norbonyl tosylate in the solvolytic reaction?
a) easy formation of non-classical carbonium ion
b) anchimetic assistance by the pi-bond
c) favourable geometry
d) all the three – A, B & C
One of the modern methods of studying free radicals, formed
during the course of a reaction is
a) I.R spectra
b) U.V spectra
c) CIDNP
d) Microwave spectra
What is the electrphile in the haloform reaction?
a) H+
b) OHc) CH3+
d) X+
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