Some Basic Principles of Organic Chemistry – 1

1) The hybridisation of Carbon in CO32- is
a) sp
b) sp2
c) sp3
d) dsp2

2) The number of sigma and pi bonds present in cyanogen
a) 2,4
b) 3,4
c) 4,4
d) 2,3

3) The C-C bond length in diamond and graphite respectively are
a) same
b) 154 pm,142 pm
c) 142pm,154 pm
d) 353 pm, 247pm

4) The electronegativity of carbon is equal to that of
a) hydrogen
b) oxygen
c) sulphur
d) nitrogen

5) The bonds between carbon atom (1) and carbon atom (2) in compound involves the hybrid orbitals
a)
b)
c)
d) sp and sp

6) Which of the following has all the carbon atoms sp-hybridized ?
a)
b)
c)
d) All the above

7) The CI-C-CI angle in 1, 1, 2, 2-tetrachloroethene and tetrachloromethane respectively will be about
a)
b)
c)
d)

8) Which of the following possesses a sp-carbon in its structure ?
a)
b)
c)
d)

9) The compound in which C uses only its hybrid orbitals for bond formation is
a) HCOOH
b)
c)
d)

10) Cyclic hydrocarbon “A” has all the carbon and hydrogen atoms in a single plane. All the carbon-carbon bonds have the same length, less than , but more than . The CCC bond angle will be
a)
b)
c)
d)

11) The enolic form of acetone contains
a)
b)
c)
d)

12) The shortest C – C bond distance is found in
a) Diamond
b) Ethane
c) Benzene
d) Acetylene

13) The C-C bond length of the following molecules is in the order
a)
b)
c)
d)

14) The hybridization of carbon atoms in a C-C single bond of        is
a)
b)
c)
d)

15) The number of bonds in
a) 4
b) 3
c) 2
d) 5

16) An
a) 1/4 s-character
b) 1/2 s-character
c) 1/3 s-character
d) 2/3 s-character

17) What hybrid orbitals will form the following compound ?
a)
b)
c)
d)

18) The number of electrons in naphthalene is
a) 4
b) 3
c) 10
d) 14

19) The number of electrons in cyclobutadienyl dianion is
a) 2
b) 4
c) 6
d) 8

20) A straight chain hydrocarbon has the molecular formula . The hybridization of the carbon atoms from one end of the chain to the other are respectively The structural formula of the hydrocarbon would be
a)
b)
c)
d)

21) Which of the following statements is not correct ?
a) A double bond is shorter than a single bond
b)
c) A double bond is stronger than a single bond
d) A covalent bond is stronger than a hydrogen bond

22) Which of the following compounds does not contain a double bond or a triple bond ?
a)
b)
c)
d) HCN

23) Which is the correct symbol relating the two Kekule structures of benzene ?
a)
b)
c)
d)

24) When the hybridization state of carbon atom changes from   and finally to sp, the angle between the hybridized orbitals
a) decreases gradually
b) decreases considerably
c) is not affected
d) increases progressively

25) The maximum number of carbon atoms arranged linearly in the molecule,
a) 5
b) 4
c) 3
d) 2

26) The aromatic character of benzene is accounted for by
a) The resonance theory
b) The hybridization of the orbitals involvement
c) Its shape
d) All the above

27) In which of the compounds given below is there more than one kind of hybridization for carbon ?
I.
ii.
iii.
iv.

a) (ii)
b) (iii) and (iv)
c) (I) and (iv)
d) (ii) and (iii)

28) The change in the state of hybridization of the asterisked carbon in the following reaction
a)
b)
c)
d)

29) The bond length between the -hybridized carbon and the other carbon atom is minimum in
a) Propane
b) Propyne
c) Propene
d) Butane

30) In which of the following is carbon most electronegative?
a) sp
b)
c)
d) same in all.

31) The molecular mass of an organic compound which contains only one nitrogen atom can be
a) 73
b) 76
c) 146
d) 152

32) An organic compound having carbon, hydrogen and sulphur contains 4 % of sulphur. The minimum molecular weight of the compound is
a) 200
b) 400
c) 600
d) 800

33) 0.50 g of an organic compound was Kjeldahlised and the evolved was absorbed in a certain volume of 1 N . The residual acid required 60 of N/2 NaOH. If the percentage of N is 56 then the volume of 1 N taken was
a) 30 ml
b) 40 ml
c) 50 ml
d) 60 ml

34) 0.59 g of the silver salt of an organic acid (mol. wt. 210) on ignition gave 0.36 of pure silver. The basicity of the acid is
a) 1
b) 2
c) 3
d) 4

35) 0.532 g of the chloroplatinate of an organic base (mol. wt. 264) gave 0.195 g of Pt on ignition. Then the number of nitrogen atoms per molecule of base is
a) 1
b) 2
c) 3
d) 4

36) A hydrocarbon having the empirical formula has a density of 1.25 g/L. The molecular formula of the hydrocarbon is
a)
b)
c)
d)

37) The percentage composition of a compound is C = 90 % and H = 10 %. A plausible formula of the compound is
a)
b)
c)
d)

38) Complete combustion of a sample of a hydrocarbon gives 0.66 g of and 0.36 g of . The empirical formula of the compound is
a)
b)
c)
d)

39) @ A dibasic acid containing C, H and O was found to contain, C = 26.7 % and H = 2.2 %. The vapour density of its diethyl ester was found to be 73. What is the molecular formula of the acid ?
a)
b)
c)
d)

40) The tetrahedral bonding in carbon atom was first shown by
a)
b) Kekule
c) Lewis
d) Pauling

41) The first Nobel prize in chemistry was awarded to
a) Hoffmann
b)
c) Baeyer
d) Madam curie

42) In which of the following compounds do all the carbon atoms have tetrahedral hybridization ?
a) 2-Methylpropane
b) Benzene
c) Ethylene
d) Acetylene

43) How many types of carbon atoms are present in 2,2,3- trimethylpentane ?
a) 1
b) 2
c) 3
d) 4

44) Which of the following contains only primary hydrogen atoms ?
a) Cyclohexane
b) Neohexane
c) Neopentane
d) Isobutane

45) The hybridization of the tertiary carbon atom in isobutane is
a) sp
b)
c)
d) none of these

46) The state of hybridization of the carbon atoms in cyclopropane is
a)
b)
c) sp
d)

47) The hybrid orbitals involved in the formation of ethene are
a)
b)
c) sp
d)

48) The state of hybridization of the central carbon atom in 1,2 – propadiene (allene) is
a)
b)
c) sp
d) none of these

49) In benzene, overlapping between carbon atoms is of the type
a)
b)
c)
d) sp – sp

50) In which of the following compounds are all the carbon atoms not – hybridized ?
a) Benzene
b) 1,3 Butadiene
c) 1,3,5-Hexatriene
d) 1,2 propadiene

51) In which of the following compounds all the carbon atoms are not sp-hybridized ?
a) Acetylene
b) Vinylacetylene
c) 1,3 butadiyne
d) Cyanogen

52) Carbon atoms having only bonds have hybridization of
a)
b)
c) sp
d) none

53) The hybrid state of carbon in the carbonyl group of a retone is of
a)
b)
c) sp
d) none

54) The change in the state of hybridization of the asterisked carbon in the following reaction is

a)
b)
c)
d)

55) In the following reactions,

the state of hybridization of carbon changes from

a)
b)
c)
d)

56) sp-hybrid bonds are present in
a) Ethane
b) Ethene
c) Ethyne
d) Benzene

57) The bond between carbon 1 and 2 in the following compound is
a)
b)
c)
d)

58) The orbital providing the most efficient overlap is
a) sp – sp
b)
c)
d)

59) Which of the following orbital overlaps between carbon and hydrogen atom gives the maximum strength to the C-H bond ?
a)
b)
c) sp – s
d) All give the same strength

60) The bond dissociation energy of the triple bond in acetylene is
a) 803
b) 251
c) 598
d) 347

61) In the series ethane, ethylene and acetylene the C-H bond energy is
a) The same in all the three compounds
b) The smallest in ethane
c) The smallest in ethylene
d) The smallest in acetylene

62) The shape of the cloud in acetylene is
a) Linear
b) Planar
c) Cylindrical
d) Doughtnut

63) The shape of the pi-electron cloud in benzene is
a) Planar
b) Cylindrical
c) Doughnut
d) Linear

64) In a double bond between two carbon atoms of ethene, there are
a) two sigma bonds perpendicular to each other
b) one sigma bond and one pi bond
c)
d)

65) The triple bond in acetylene is made up of
a) 3 sigma bonds
b) 3 pi bonds
c) 2 sigma and 1 pi bond
d) 1 sigma and 2 pi bonds

66) In the ethene molecule, the H – C – C angle is
a)
b)
c)
d) none

67) The carbon atoms in a benzene molecule are inclined at an angle of
a)
b)
c)
d)

68) In benzene, the hybrid orbitals of each carbon constitute
a) two sigma and one pi bond
b) one sigma and two pi bonds
c) three sigma bonds
d) none of the above

69) How many approximately angles does benzene molecule have ?
a) 18
b) 12
c) 9
d) 15

70) In which of the following is the H-C-C angle the maximum ?
a)
b)
c)
d)

71) The C-C bond distance is the longest in
a)
b)
c)
d)

72) The C-H bond distance is the shortest in
a) Ethane
b) Methane
c) Ethene
d) Ethyne

73) Which of the following has the shortest carbon – carbon distance ?
a) Ethane
b) Ethene
c) Ethyne
d) Benzene

74) The carbon – carbon bond length in benzene is
a)
b)
c)
d)

75) In which of the following compounds do all the atoms lie in the same plane ?
a)
b)
c)
d)

76) @ How many s -bonds are present in the following molecule?

a) 10
b) 12
c) 2
d) 4

77) @ The number of -bonds in naphthalene molecules is
a) 19
b) 11
c) 21
d) 15

78) How many electrons are there in the following structure ?

a) 2
b) 4
c) 6
d) 8

79) Q@ How many and bonds are there in the molecule of tetracyanoethylene ?

a)
b)
c)
d)

80) Q@ How many and bonds are present in a toluene molecule ?
a)
b)
c)
d)

81) Which of the following compounds has the maximum number of bonds ?
a)
b)
c)
d)

82) Benzene was discovered by
a) Ramsay
b) Dalton
c) Faraday
d) Priestley

83) The centric formula of benzene was proposed by
a) Dewar
b) Ladenburg
c) Kekule
d) Armstrong and Baeyer

84) The representation of benzene by a regular hexagon with a circle inside shows
a) Kekule formula
b)
c)
d) Thiele’s partial bond formula

85) Naphthalene is an example of a/an
a) Aliphatic compound
b) Alicyclic compound
c) Polynuclear hydrocarbon
d) Heterocyclic compound

86) In benzene, all the C-C bonds have the same length because of
a) the inductive effect
b) Tautomerism
c) Isomerism
d) Resonance

87) The carbon atoms of 1,3-butadiene are numbered as shown below. Which of the following statements regarding the compound is incorrect?
a) Carbon atoms 1,2,3 and 4 are all sp2 hybridised
b) Carbon atoms 1 and 2 are sp2 hybridised
c) The single bond between C2 and C3 is of the same length as the carbon-carbon bond length in ethane
d) It is a conjugated diene

88) In benzene, resonance involves
a)
b)
c) delocalization of n- electrons
d)

89) Which one of the following compounds has delocalized electrons ?
a) Methane
b) Benzene
c) Ethane
d) Cyclohexane

90) Which one of the following compounds shows resonance ?
a) Ethane
b) Cyclohexene
c) Toluene
d) Ethyne

91) Which of the following has the maximum resonance energy ?
a) 1 ,3 – Butadiene
b) 1, 3 , 5 – Hexatriene
c) 1, 3-Cyclohexadiene
d) Benzene

92) Which of the following has the least heat of hydrogenation per double bond (on average) ?
a) 1, 3-Cyclohexadiene
b) Benzene
c) 1, 3, 5-Cyclohexatriene (hypothetical)
d) 1, 3- Butadiene

93) The aromatic character of benzene is due to the
a) Presence of a ring
b) Presence of three conjugated double bonds
c)
d) None of the above

94) According to Huckel rule, a cyclic planar conjugated polyene is aromatic if it contains
a)
b)
c)
d)

95) Mark the correct statement:
a) Benzene is aromatic while naphthalene is not
b) Benzene and cyclohexane are both aromatic
c) Benzene behaves more like an alkane than an alkene
d) Benzene has a tetrahedral geometry like an alkane

96) Which one among the following is an aromatic compound ?
a) Cyclopentadiene
b) Cyclopentadienyl anion
c) Cyclopentadienyl cation
d) Cyclopentadienyl radical

97) The heat of hydrogenation of benzene is 51 kcal/mol while its resonance energy is 36 kcal/mol. Then, the heat of hydrogenation of cyclohexene is
a) 29 kcal/mol
b) 14 kcal/mol
c) 36 kcal/mol
d) 22 kcal/mol

98) Which among the following molecules /species is/are not aromatic ?
a) Cyclobutadienyl dianion
b) Cyclooctadienyl dianion
c) Cycloheptatrienyl cation
d) None of the above

99) Which of the following is an antiaromatic compound ?
a) Cyclobutadiene
b) Cycloheptatriene
c) Cyclooctatetraene (tub shaped )
d) Cyclodecapentaene

100) Which of the following is a non-aromatic compound ?
a) Naphthalene
b) Cycloheptatriene
c) Cycloheptatrienyl cation
d) Furan


Answer :

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