chemical bonding and molecular structure

1. CHEMICAL BONDING CHEMISTRY - 1C
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1. The unit of dipolemoment is
1) Einstin 2) Dalton 3) Debye 4) Curie
2. One Debye (D) equal to
1) 1 × 10–4 esu.cm 2) 1 × 10–18 esu.cm
3) 1 × 10–10 esu.cm 4) 1 × 10–16 esu.cm
3. Carbon tetrachloride has no dipole moment
because of
1) its regular tetrahedral structure
2) Its planar structure
3) similar sizes of carbon and chlorine atoms
4) similar electron affinities of carbon and
chlorine
4. The unequal sharing of the bond pair of
electons between two atoms in a molecule
causes,
1) Dipole 2) radical formation
3) Covalent bond
4) Decomposition of molecule
5. S.I. unit for dipole moment is
1) e.s.u-cm 2) Coulomb-cm
3) coulomb-metre 4) e.s.u – metre
6. Molecule with zero dipole moment is
1) BCl3 2) BeCl2
3) CCl4 4) All of these
7. Which one of the following has  = 0
1) CH2Cl2 2) SO3 3) NH3 4) H2O
8. Bent molecule having dipole moment among
the following
1) F2O 2) H2O
3) Cl2O 4) All the above
9. Which of the following molecule has zero
dipolemoment (2005)
1) BeCl2 2) HCl 3) NH3 4) H2O
10. In which of the following pairs, both
molecules possess dipole moment? (2007)
1) 2 2CO ,SO 2) 3 3BCl ,PCl
3) 2 2H O,SO 4) 2 2CO ,CS
11. Which of the following has highest dipole
moment ?
1) BF3 2) CO2 3) CCl4 4) NF3
12. Molecule with dipole moment among the
following
1) SF6 2) PCl5 3) CCl4 4) BF3
13. (A) : The dipolemoment value of NH3 is
greater than zero
(R) : In NH3 bond angle is approximately
104°
14. (A) : SiF4 is non polar even though fluorine
is much more electronegative than silicon
(R) : The four bond dipoles cancel one
another in SiF4 molecule
15. (A) : SO2 molecule has unsymmetrical shape
(R) : The dipole moment of SO2 molecule is
not equal to zero
16. The following are some statements about
dipole moment.
i) The dipolemoment of a molecule in which
the central atom has no lone–pair, is zero
ii) The dipolemoment of a diatomic molecule
having non–polar bonds is zero
iii) The dipolemoment of a diatomic molecule
having polar covalent bonds is non–zero.
1) all the three statements are correct
2) only ii is correct
3) only ii and iii are correct
4) only i and iii correct.
17. In SF6 molecule
1) bonds are polar but molecule is non polar
2) bonds are polar and molecule is also polar
3) bonds are non polar but molecule is polar
4) bonds are non polar and molecule is non polar
18. Dipolemoment is least in
1) para – dichlorobenzene
2) meta – dichlorobenzene
3) ortho – dichlorobenzene
4) monochloro benzene
EXERCISE

2. CHEMISTRY - 1C CHEMICAL BONDING
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19. The dipole moment of HX molecule is 1.92D
and bond distance is 1.2A0. What is the
percentage ionic character of HX?
1) 33% 2) 25% 3) 70% 4) 66%
20. Which of the following will have zero dipole
moment?
1) 1, 1– dichloroethylene
2) cis-1, 2-dichloroethylene
3) trans-1, 2-dichloroethylene
4) none of these
21. The molecules BF3 and NF3 are covalent
compounds. But BF3 is non-polar and NF3
is polar. The reason is
1) Boron is a metal and nitrogen is a gas in
uncombined state
2) BF bonds have no dipole moment where
as NF bonds have dipole moment
3) Atomic size of boron is smaller than that of
nitrogen
4) BF3 is planar but NF3 is pyramidal in shape
22. BeF2 has zero dipole moment where as H2O
has a dipole moment because
1) H2O is a linear molecule
2) H2O is a bent molecule
3) F is more electronegative than O
4) Hydrogen bonding is present in H2O
23. From the following given statements of the
order of dipolemoments.
i) HF > H2O > NH3
ii) CH2Cl2 > CHCl3>CCl4
iii)
> >
Cl
Cl
Cl
Cl
The correct combination is
1) all are correct 2) i, ii are correct
3) only iii is correct 4) only i is correct
24. A molecule MX3 has zero dipole moment.
The % of 's' character in the hybridized
orbitals of M is
1) 25% 2) 33.3% 3) 50% 4) 75%
25. Dipole moment of H2X is 1.0D. If the bond
angle is 90o, the approximate bond moment
of H-X bond is (Cos 45o= 0.7)
1) 0.4D 2) 0.5D 3) 0.7D 4) 0.6D
26. The dipolemoment of HX is 1.2D. If the ionic
character of the bond is 25%, then it's bond
length is
1) 10A0 2) 10–10m 3) 10–8m 4) 10–6m
27. Which bond angle  would result in the
maximum dipolemoment for the triatomic
molecule XY2
1)   0
90 2)   0
120
3)   0
150 4)   0
180
28. If the bond length and dipolemoment of a
diatomic molecule are 1.25Ao and 1.0D
respectively, what is the percent ionic
charcter of the bond ? (2003)
1) 10.66 2) 12.33 3) 16.66 4) 19.33
29. The highest dipolemoment is of (AFMC)
1) CF4 2) CH3OH 3) CO2 4) CH3F
30. Born - Haber cycle is used to determine
(AFMC)
1) Electron affinity 2) Lattice energy
3) Crystal lattice energy
4) All the above
31. Chemical bond implies (KCET)
1) Attraction and repulsion
2) Attraction and repulsion balanced at a
particular distance
3) Attraction 4) Repulsion
32. The compound having highest dipole
moment is (AIIMS)
1)
3
3
Cl CH
| |
C = C
| |
CH Cl
2)
3
3
H CH
| |
C = C
| |
CH H
3)
H
H
C=O 4)
3
3
CH H
| |
C = C
| |
CH H

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33. The O–H bond length in H2O is xA0. The
O–H bond length in H2O2 is
1) < xA0 2) xA0 3) > xA0 4) 2x
34. The C–C bond distance is largest in
1) C2H2 2) C2H4
3) C2H2Br2 4) C2H6
35. Bond polarity is least in
1) N–H 2) O–H 3) H–F 4) C–H
36. Bond energy is highest in the molecule
1) F2 2) Br2 3) I2 4) Cl2
37. Bond energy of C–C bond is highest in
1) H3C–CH3 2) H2C=CH2
3) CH  CH 4) C2H5Cl
38. Bond energy is highest in the overlaping
1) sp3– s 2) sp2– s
3) sp – s 4) equal in all
39. Bond energy is least in the following
1) HF 2) HCl 3) HBr 4) HI
40. The highest bond energy is in
1)   
| |
C C
| |
2)   
 
N N
| |
3)   
 
 
O O
4)
 
 
 
 
F F
41. Which of the following has least bond
energy? (2000)
1) F2 2) H2 3) N2 4) O2
42. Which of the following hydrocarbon has
least C-C bond length ? (2001)
1) C2H6 2) C2H4 3) C6H6 4) C2H2
43. The correct order of bond lengths is
1) H–Cl > H–Br > H – I
2) H–I > H – Br > H – Cl
3) H–I > H–Cl > H–Br
4) H–Br > H–I > H-Cl
44. Bond energy is least in the following
1) C – C 2) N  N
3) O = O 4) F – F
45. The decreasing order of bond dissociation
energies of C–C, C–H and H–H bonds is
1)       H H C H C C (2007)
2)        C C C H H H
3)         C H C C H H
4)        C C H H C H
46. Which of the following has largest bond
angle?
1) NO2
+ 2) NO2 3) NO2
– 4) NO3
–
47. Arrange the following in order of decreasing
N-O bond length NO2
+ , NO2
– , NO3
–
1) NO3
– > NO2
+ > NO2
–
2) NO3
– > NO2
– > NO2
+
3) NO2
+ > NO3
– > NO2
–
4) NO2
– > NO3
– > NO2
+
48. The Cl – O bond order in perchlorate ion
1) 1 2) 2 3) 1.75 4) 2.5
49. Which of the following is more stable
1) HF 2) HCl 3) HBr 4) HI
50. (A) : Dinitrogen is chemically unreactive at
ordinary temperature and is very stable
(R) : The bond dissociation energy is more
in N2 molecule (1)
51. C2H5Br + Q1  C2H5
. + Br.
C2H5Br + Q2
 C2H5
(+) + Br(–),
Then relation between Q1 & Q2 is
1) Q1 > Q2 2) Q1 < Q2
3) Q1 = Q2 4) Q1 + Q2 = 0
52. In O2, H2O2 and O3, the correct order of
'oxygen–oxygen' bond length is
1) O2 > O3 > H2O2 2) O3 > H2O2 > O2
3) H2O2 > O3 > O2 4) O2 > H2O2 > O3
53. Bond length of H2 is 0.074nm, Bond length
of Cl2 is 1.98A0. Bond length of HCl is
1) 2.72Ao 2) 136pm
3) 1.027nm 4) 0.136Ao

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54. Energy required to dissociate 4gm of
gaseous hydrogen in to free gaseous atoms
is 208Kcal at 250C.The bond energy of H–
H would be
1) 54 Kcal/mol 2) 104 Kcal/mol
3) 208 Kcal/mol 4) 20.8 Kcal/mol
55. Average C–H bond energy is 416 kJ.mol–1.
Which of the following is correct? (2004)
1) CH4(g) + 416 kJ  C(g) + 4H(g)
2) CH4(g) C(g) + 4H(g) + 416 kJ
3) CH4(g) + 1664 kJ  C(g) + 4H(g)
4) CH4(g) C(g) + 4H(g) + 1664 kJ
56. The resonance hybrid of nitrate ion is
1) 2)
3) 4)
57. The bond dissociation of the molecules A2,
B2, C2 are 498, 158, 945 KJ/ mole
respectively. If so, the correct decreasing
order of their bond orders is
1) A2, B2, C2 2) C2, B2, A2
3) C2, A2, B2 4) B2, C2, A2
58. The table shown lists the bond dissociation
energies (Ediss) for single covalent bonds
formed between carbon and atoms of
elements A,B,C and D. Which element has
the smallest atom.
Bond between C Ediss (KJmole-1)
and other atom
A) C –A 240
B) C – B 328
C) C – C 276
D) C – D 485
1) C 2) D 3) A 4) B
59. The correct order of N -O bond length in
NO, NO–
2 , NO–
3 and N2O4 will be (BHU)
1) NO > N2O4 > NO2 > NO3
–
2) NO > NO–
3 > N2O4 > NO–
2
3) NO3
– > NO2
– > N2O4 > NO
4) N2O4 > NO2
– > NO3
– > NO
60. Which of the following has lowest melting
point? (CPMT)
1) Argon 2) NaCl 3) Iron 4) Silicon
61. The C–H bond distance is largest in
1) C2H2 2) C2H4 (MLNR)
3) C6H6 4) C2H4Br2
62. In compounds of type ECl3, where E = B, P.
As or Bi, the angles Cl - E - Cl for different
E are in the order (BHU)
1) B > P = As = Bi 2) B > P > As > Bi
3) B < P = As = Bi 4) B < P < As < Bi
63. The geometry of H2S and its dipole moment
are (AFMC)
1) Angular and non-zero
2) Angular and zero
3) Linear and non-zero
4) Linear and zero
64. The correct order of increasing C-O bond
length of CO, CO 2
3 and CO2 (IIT)
1) CO 2
3 < CO2 < CO 2) CO2 < CO 2
3 < CO
3) CO < CO 2
3 < CO2 4) CO < CO2 < CO 2
3
65. The number and type of bonds between two
carbon atoms in CaC2 are (IIT)
1) One sigma ( ) and one pi (  ) bonds
2) One sigma ( ) and two pi (  ) bonds
3) One sigma ( ) and a half pi (  ) bonds
4) One sigma ( ) bond only
66. KF combines with HF to form KHF2. The
compound contains the species (IIT)
1) K+, F– and H+ 2) K+, F– and HF
3) K+ and [HF2]–1 4) [KHF]+ and F–

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67. The bond order of individual C–C bond in
benzene is (IIT)
1) One 2) Two
3) Between one and two 4) None of these
68. In which of the following species the inter
atomic bond angle is 1090.28! (AIEEE)
1) NH3 (BF3) 2) (NH4)+ (BF3)
3) NH3 (BF4)– 4) (NH2)– (BF3)
69. Which one of the following pairs of
molecules will have permanent dipole-
moments for both members? (AIEEE)
1) SiF4 and CO2 2) SiF4 and NO2
3) NO2 and CO2 4) NO2 and O3
70. Which of the following compounds has the
smallest bond angle in its molecule (AIEEE)
1) NH3 2) SO2 3) OH2 4) SH2
PASSAGE TYPE QUESTIONS
PASSAGE - I : T Sodium chloride crystallises into
F.C.C lattice with Na+ occupying corner of a cube
and the centre of each face, where as Cl– is occupy
the centre of each edge and centre of the cube.
The rc/ra value for NaCl is 0.53 and coordination
number is 6,6.
1. If all the ions present in one plane that is
passing through the centre are removed, the
formula of the resulting unit cell is
1) NaCl 2) Na2Cl3 3) Na3Cl2 4) NaCl2
2. If all the face centred ions along one of the
axis are removed. The stoichiometry of the
resulting solid is
1) NaCl2 2) Na2Cl 3) Na4Cl3 4) Na3Cl4
3. In NaCl crystal lattice each sodium ion is
surrounded by ––– number of chloride ions
in –---––– fashion
1) 8, tetrahedral 2) 6, octahedral
3) 8, square planar
4) 6, distorted octahedron
4. In NaCl unit cell, the edge length is
1) 2rc+ 2ra 2) rc+ra
3)
2
c ar r
4)  3 c ar r
PASSAGE - II : According to V.B.T. a covalent
bond is formed by the overlapping of half filled
atomic orbitals with electron spinning in the
opposite direction. The strength of a bond depends
on extent of overlapping. Double bond energy is
not twice that of single bond energy because a
double bond is made up of a weak  bond and
strong  bond.
5. According to V.B.T, in the formation of CH4
molecule the type of overlappings observed
are
1) p–s, s–s 2) p – s
3) sp3 – s, s–s 4) sp2 – s, s – s
6. The expected bond angle in NH3 molecule
according to V.B.T is
1) 900 2) 1070
3) 1090.28' 4) 1200
7. More energy is required to break the bond
between the carbon atoms in
1) C2H6 2) C2H4
3) C6H6 4) C2H2
8. Bond energy is highest in
1) F2 2) Cl2 3) O2 4) N2
PASSAGE - III : Hydrogen bond is a weak
electrostatic force of attraction between covalently
bonded hydrogen and more electronegative species
like F,O and N. It play an important role in
influencing many physical constants. It is a weaker
bond than covalent bond but stronger than
vanderwaal forces of attraction.
9. Hydrogen bonding is absent in
1) CH3OH 2) CH3F
3) CH3NH2 4) (CH3)2NH
10. Chelation is observed in
1) P - nitrophenol 2) O - nitrophenol
3) Benzaldehyde 4) HF

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11. During the boiling of a liquid, the bonds
broken are
1) Intramolecular Hydrogen bonding
2) Intermolecular Hydrogen bonding
3) Covalent bond
4) Dative bond
12. Which of the following can exsist as a
Hexamer in vapour state
1) H2O 2) HF
3) CH3CHO 4) C2H5OH
PASSAGE - IV: The geometry of a molecule
depends upon the repulsions between electron pair
present in the valance shell of the central atom. LP
– LP repulsions are greater than LP–BP which are
greater than BP – BP. A pi bond can not decide the
geometry of a molecule because pi bond has no
independent exsistance. Deviations in bond angle
is due to the presence of lone pairs.
13. Which of the following differ from the rest
in geometry.
1) BF3 2) SO3 3) SO3
2– 4) CO3
2–
14. In which of the following orientation of
electron pairs around the central atom is
tetrahedral
1) NH3 2) CH3
–
3) CH3
+ 4) Both NH3 and CH3
–
15. Which of the following molecule is linear in
shape.
1) I3
– 2) CO2
3) Both I3
– and CO2 4) SO2
16. Square planar species among the following
is
1) XeF4 2) NiCl4
2–
3) Both XeF4 and NiCl4
2– 4) CH4
ANSWERS
1) 3 2) 2 3) 1 4) 1 5) 3
6) 4 7) 2 8) 4 9) 1 10) 3
11) 4 12) 2 13) 3 14) 1 15) 1
16) 3 17) 1 18) 1 19) 1 20) 3
21) 4 22) 2 23) 2 24) 2 25) 3
26) 2 27) 1 28) 3 29) 2 30) 4
31) 2 32) 3 33) 2 34) 4 35) 4
36) 4 37) 3 38) 3 39) 4 40) 1
41) 1 42) 4 43) 2 44) 4 45) 1
46) 1 47) 2 48) 3 49) 1 50) 1
51) 2 52) 3 53) 2 54) 2 55) 3
56) 3 57) 3 58) 2 59) 3 60) 1
61) 4 62) 2 63) 1 64) 4 65) 2
66) 3 67) 3 68) 1 69) 4 70) 4
PASSAGES
1) 1 2) 4 3) 2 4) 1 5) 1
6) 1 7) 4 8) 4 9) 2 10) 2
11) 2 12) 2 13) 3 14) 4 15) 2
16) 1
ANSWERS
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