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Molecular Orbital Theory
1)
N 2
2)
O 2
3)
F2
4)
He2

2. The bond order of superoxide ion [ O 2 ] is
2) 1.5
3) 2
4) 2.5
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1) 1
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1. Which of the following has zero bond order?
3. Bonding electrons present in N2 molecule are
1) 2
2) 4
3) 6
4) 10
3) Li2
4) F2
4 . Bond order of H2 is similar to
1) N2
2) O2
5. Which of the following is paramagnetic with bond order 2?
2)
O 2
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1) O2
3) N2
4) O2+
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6. Which of the following has more number of unpaired electrons in their
.s
a
molecular orbitals?
1) C2
2) N2
3) O2
4) F2
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7. For a homodiatomic molecule with a total number of 16 electrons, after
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filling  *2s, the next electron enters in to
1)
2px
2)
2py
3)
2px or 2py
4)  2Pz
8. Which of the following pair of molecular orbitals ore degenerate?
1) 1s, * 1s
2)  2s,  *2s
3)
2py , *2py
4)
2px
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,
 2py
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9.
H 2 and H 2 ions
have the same bond order of 0.5, but
H 2
is slightly less

stable than H 2 .This is due to
1) It is anion.
2) One electron in the bonding orbital.
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3) One electron in the anti bonding orbital.
4) Two electrons in bonding orbital.
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10. Addition of wave functions of yA and yB of atomic orbitals A and B form
1) Bonding molecular orbitals
2) Anti-bonding molecular orbitals
3) Both bonding and antibonding molecular orbitals
4) Hybrid orbitals
11. The filling up of molecular orbitals with electrons follows
b) Hund’s rule
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a) Aufbau principle
2) a and c only
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1) a only


.s
a
12. The bond length in O 2 , O2 ,O 2 and
c) Pauli’s principle
3) b and c only
O2 2 follows
the order
1)
O 2 2  O 2  O 2  O 2
2)
O 22  O 2  O 2  O 2 2
3)
O 2  O 2  O 22  O 2
4)
O 2 2  O 2  O 2  O 2
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4) a, b and c
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13. Which of the following is incorrect regarding molecular orbitals?
1) Bonding molecular orbital has less energy than the combining atomic
orbital.
2) Bonding molecular orbital has no nodal plane.
3) Anti-bonding molecular orbitals has nodal plane.
4) Anti-bonding molecular orbital stabilizes the molecules.
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14. Which of the following has a bond order of 0.5?
1) H2
2)
H 2
3) N2
4) Ne2
15. When N2 changes to N2+, then N-N bond distance and O2 changes to
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O2+, then O-O bond distance
1) Increases, decreases
2) Decreases, increases
3) Increases in both cases
4) Decreases in both cases
1) O2-
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16. The highest bond strength is for
2) B2
17. Bond order of Be2 is
1) 0
2) 1
3) N2+
4) He2
3) 2
4) 3
18. Which one of the following correctly represents, the increasing order of
their stability
O 22 ,O 2 ,O 2 ,O 2
2)
O 22 , O 2 ,O 2 , O 22
hi
1)
3)
O 2 , O 2 , O 2 , O 22
4)
O 2 ,O2 ,O 2 ,O 22
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19. Which of the following statement is correct?
.s
a
1) The peroxide ion has bond order of ½ while the oxygen molecule has bond
order of zero
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2) The peroxide ion has a longer and weaker bond than the oxygen molecule
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3) The peroxide ion as well as the oxygen molecule are paramagnetic
4) The bond length of the peroxide ion is smaller than that of O 2 molecule
20. Bond order in peroxide ion is
1) Larger than in O2 molecule
2) Smaller than in superoxide ion
3) Equal to that in N2 molecule
4) Greater than in F2 molecule
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21. Bond order and magnetic behaviour of O2 is
1) 2, diamagnetic
2) 1, diamagnetic
3) 2, paramagnetic
4) 1, paramagnetic
22. The number of antibonding electron pairs in
O2 2
1) 2
2) 3
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molecular orbital theory is
ion on the basis of
3) 4
4) 5
1) 2
2) 4
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23. According, to MOT, the number of unpaired electrons in O2 molecule is
3) 12
4) Zero
24. According, to MOT, the bond order of a molecule is equal to
1) Total no. of bonding electrons
2) Total no. of anti-bonding electrons
3) Half the difference between no.of bonding electrons and antibonding
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electrons
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4) The difference between no.of bonding and antibonding electrons.
25. Molecule/ion
O2 1
w
B)
.s
a
A) O2
Bond order
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C) O2D)
1) 2.5
2) 1.0
3) 2
O2 2
4) 1.5
A
B
C
D
1) 3
2
1
4
3) 2
3
1
4
A
B
C
D
2)
3
1
4
2
4)
2
3
4
1
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26. The bond order in
1) N2+
O2 1
2)
is same as in
CN
3) NO+
4) CO
27. Which of the following species is paramagnetic?
2)
CN
3) CO
4)
O2 2
28. Which of the following is not paramagnetic?
2) CO
3)
O2 1
4) NO
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1) N2+
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1) O2-
29. Which of the following species has the lowest bond order?
1) O2
2)
O2 1
3) O2-
4)
O2 2
30. Which set of the following species has a bond order of 2.5?
1)
N 2 , NO,O 2
2)
O 2 , NO,CN 
3)
N 2 ,CN  ,O2
4)
CN  , N 2 , O 2
31. Which of the following set are isoelectronic?
N 2 , O 22
2)
N 2 , O 22
hi
1)
3) N2+, O2+
4)
N 2 , O 2
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32. Which of the following diatomic species do you expect to have the longest
.s
a
bond length?
1) N2
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33. According, to MOT
2)
O2 1
3) O2-
4) N2+
O2 1 has
2) Bond order of 2.5
3) Stability less than NO
4) Diamagnetic character
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1) Three unpaired electrons
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34. Which one of the following statement regarding molecular orbital is
incorrect?
1) The energy of the anti bonding M.O is more than the combining atomic
orbital and it destabilizes the molecule.
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2) The energy of the bonding M.O is less than the combining atomic orbital
and it stabilizes the molecule.
3) The increase in the energy of anti bonding molecular orbital is same as the
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decrease in the energy of bonding molecular orbital
4) The no. of bonding M.O’s is twice to Anti bonding M.O’s
35. For a homodiatomic molecule with a total number of electrons 14 after
*
filling  2s M.O the next electron goes to
1)  2 pz
2)
2px
3)
 2py
4)
2px or 2py
36. Which of the following ion has not bond order of 2.5?
2)
O2 1
3) N2+
4) N2-
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1) O2-
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37. The common features among the species
CN - , CO and NO + are :
2) Bond order 2 and isoelectronics
3) Bond order 2, 5 and isoelectronics
4) Bond order1.5 and isoelectronics
.s
a
1) Bond order 3 and isoelectronics
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38. Which of the following species has the shortest bond length?
1) N2+
2) N2
3) N2-
4)
39. Among the following which one is paramagnetic?
1) He2
2) O2-
3) Li2
4) Ne2
40. Which of the following should be most stable?
1) He2
2) H2
3)
He2
4) H2+
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N 22-
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KEY
2)2
3)3
4)4
5)1
11) 4
12)1
13) 4
14)2
21)3
22) 2
23)1
8)4
9) 3
10) 1
15)1 16)3
17)1
18) 1
19)2
20) 2
25) 2
27)1
28)2
29)4
30) 1
26)1
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32) 2
7) 4
33)2
34)4
35)4
36)1
37) 1
38) 2
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w
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.s
a
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31) 2
24) 3
6) 3
co
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1) 4
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39)2
40)2