Download PTU (I. K. Gujral Punjab Technical University) MSc -Chemistry 2nd Semester May 2019 71663 SYMMETRY AND GROUP THEORY Question Paper.
Roll No. Total No. of Pages : 02
Total No. of Questions : 09
M.Sc.(Chemistry) (2015 to 2017) (Sem.?2)
SYMMETRY AND GROUP THEORY
Subject Code : MSCH-202
M.Code : 71663
Time : 3 Hrs. Max. Marks : 100
INSTRUCTIONS TO CANDIDATES :
1. Attempt any FIVE questions in all, including question no. 1 which is
compulsory and selecting one each from units I-IV
1. Answer briefly : 10?2=20
a. Define point group and space group.
b. What kind of improper rotation axis is present in ethane molecule?
c. Write any two important rules for the great orthogonality theorem.
d. Write all the symmetry elements present in CCl
4
molecule.
e. What is the difference between proper and improper rotation axis?
f. What is the point group of ethylene molecule? How its point group is changed on
dimerization?
g. Write the irreducible representation formed by the [Ni(CN)
4
]
2?
.
h. How d-orbital split in octahedral environment according to the symmetry?
i. What does the symbol S, P, D and F stands for in Free Ion terms?
j. What do you mean by the mulliken symbol T
lg
and E
u
in the character table?
UNIT-I
2. a. Consider the following sequential structural changes (I ? II ? III). For each series
indicate :
(i) Point group of each structure 5
(ii) The specific symmetry elements lost or gained in the transition I ? II. 5
FIG.
Cl
Cl
Cl
B
I
Cl
Cl
F
B
Br
Cl
F
B
II III
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1 | M-71663 (S17)-803
Roll No. Total No. of Pages : 02
Total No. of Questions : 09
M.Sc.(Chemistry) (2015 to 2017) (Sem.?2)
SYMMETRY AND GROUP THEORY
Subject Code : MSCH-202
M.Code : 71663
Time : 3 Hrs. Max. Marks : 100
INSTRUCTIONS TO CANDIDATES :
1. Attempt any FIVE questions in all, including question no. 1 which is
compulsory and selecting one each from units I-IV
1. Answer briefly : 10?2=20
a. Define point group and space group.
b. What kind of improper rotation axis is present in ethane molecule?
c. Write any two important rules for the great orthogonality theorem.
d. Write all the symmetry elements present in CCl
4
molecule.
e. What is the difference between proper and improper rotation axis?
f. What is the point group of ethylene molecule? How its point group is changed on
dimerization?
g. Write the irreducible representation formed by the [Ni(CN)
4
]
2?
.
h. How d-orbital split in octahedral environment according to the symmetry?
i. What does the symbol S, P, D and F stands for in Free Ion terms?
j. What do you mean by the mulliken symbol T
lg
and E
u
in the character table?
UNIT-I
2. a. Consider the following sequential structural changes (I ? II ? III). For each series
indicate :
(i) Point group of each structure 5
(ii) The specific symmetry elements lost or gained in the transition I ? II. 5
FIG.
Cl
Cl
Cl
B
I
Cl
Cl
F
B
Br
Cl
F
B
II III
2 | M-71663 (S17)-803
b. For the following molecules, sketch all the symmetry elements and list all the
symmetry operations associated with each symmetry element :
i) CHCl
3
5
ii) PF
5
5
3. a. Take the example of ethane molecule and sketch the proper and improper rotation
axis present in the molecule. 10
b. What is the point group of (i) 1,2-Dichloroethane, (ii) cyclobutadiene and (iii) PF
5
?
Write all the symmetry elements present in the molecules. 10
UNIT-II
4. a. Construct the character table for the CHCl
3
molecule having point group C
3v
. 10
b. What are the important rules for irreducible representation and their characters?
Verify each rule by taking example of HCHO molecule. 10
5. a. Describe the relationship between reducible and irreducible representations by taking
the example of MX
4
type of molecule. 10
b. Write the matrix notations for the geometric transformation of symmetry element, E,
i, ?
v
and C
2
. 10
UNIT-III
6. a. Write the symmetry adapted linear combination belongs to C
4
H
4
molecule. 10
b. What is the symmetry based selection rules for cyclization reactions? Explain with
the help of suitable example. 10
7. a. Construct the irreducible representation formed by the AB
3
type of trigonal planar
molecule. Also calculate the SALCs on atom B. 10
b. Draw the molecular orbitals for the ?-bonding in square planar AB
4
molecule. 10
UNIT IV
8. a. Draw the correlation diagram for a d
2
ion in an tetrahedral environment. 10
b. Discuss the splitting of free ion terms (
1
S,
1
G,
3
P) of d
2
ion in D
4h
and T
d
point
groups. 10
9. a. Construct the energy level diagram of e and t
2
orbitals resulting from splitting of d-
orbital in octahedral environment. 10
b. What is orbital and spin degeneracy? Explain by taking example of e
g
configuration.
10
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.
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This post was last modified on 05 December 2019