Hydrocarbons MCQs – 5

1) An alkene having molecular formula C7H14 was subjected to ozonolysis in the presence of zinc o dust. An equimolar amount of the following two compounds was obtained.

The IUPAC name of the alkene is

a) 3, 4-dimethyl-3-pentene
b) 3, 4-dimethyl-2-pentene
c) 2, 3-dimethyl-3-pentene
d) 2, 3-dimethyl-2-pentene.

2) Benzene can be converted into toluene by
a)
b) Sabatier and Sendrens reaction
c) Reimer-Tiemann reaction
d) Friedel-Crafts reaction.

3) A catalyst that can be employed for Friedel-Crafts acylation is
a)
b)
c)
d)

4) Benzene reacts with n-propyl bromide in presence of anhydrous AICI3 to predominantly yield
a) n-Propylbenzene
b) Ethylbenzene
c) Isopropylbenzene
d) Methylbenzene.

5) The Friedel-Crafts reaction of benzene with ethylene in presence of HCI and anhyd. AICI3 gives
a) Styrene
b) Stilbene
c) Ethylbenzene
d) 1,1 -Diphenylethylene.

6) The Friedel-Crafts reaction of benzene with isobutyl chloride produces
a) Isobutylbenzene
b) tert-Butylbenzene
c) n-Butylbenzene
d) sec-Butylbenzene.

7) Benzene reacts with acetyl chloride or acetic anhydride in the presence of anhydrous AICI3 to give
a)
b)
c)
d)

8) @ Oxidation of benzene with air at 725 K in presence of V2O5 as catalyst gives
a) Maleic acid
b) Malic acid
c) Malonic acid
d) Maleic anhydride.

9) Which of the following on oxidation with hot alkaline KMnO4 gives benzoic acid ?
a) Toluene alone
b) Ethylbenzene alone
c) Isopropylbenzene alone
d) All the three above.

10) Which of the following on oxidation with alkaline KMnO4 followed by acidification with dil. HCI does not give benzoic acid?
a) Toluene
b) Ethylbenzene
c) Isopropylbenzene
d) tert-Butylbenzene.

11) In the reaction, B is
a) Benzoic acid
b) Benzoyl chloride
c) Benzaldehyde
d) Chlorobenzene.

12) Ozonolysis of benzene under reducing conditions gives
a) One mole of glyoxal
b) Two moles of glyoxal
c) Three moles of glyoxal
d) Three moles of oxalic acid.

13) Ozonolysis of toluene gives
a) Only glyoxal
b) Only methylglyoxal
c) Both glyoxal and methylglyoxal
d) None of the above.

14) Ozonolysis of o-xylene gives
a) Glyoxal only
b) Methylglyoxal only
c) Dimethylglyoxal only
d) All the three above.

15) Amongst the following compounds which can be most easily sulphonated is
a) Benzene
b) Nitrobenzene
c) Toluene
d) Chlorobenzene.

16) The compound with the highest boiling point is
a) n-Hexane
b) n-Pentane
c) 2, 2-Dimethylpropane
d) 2-Methylbutane.

17) The reaction
is called

a) Hydroxylation
b) Epoxidation.
c) Bayer-Villiger Oxidation
d) Both b and c

18) Which of the following compounds on treatment with warm dil. H2SO4 in presence of HgSO4 will give 2-butanone?
a) 2-Butyne alone
b) 1-Butyne alone
c) 2-Butanol alone
d) Both (a) and (b)

19) Acidic hydrogen is present in
a) Ethyne
b) Ethene
c) Benzene
d) Ethane.

20) Anti- addition of HBr is not observed in
a) Propene
b) 1-Butene
c) But-2-ene
d) Pent-2-ene.

21) The highest boiling point is expected for
a) Iso-octane
b) n-Octane
c) 2, 2, 3, 3-Tetramethylbutane
d) n-Butane.

22) The reaction conditions leading to the best yield of C2H5CI are
a)
b)
c)
d)

23) Which of the following compounds reacts with sodium to liberate hydrogen gas ?
a) Ethane
b) Propylene
c) Acetylene
d) Benzene.

24) Benzene does not undergo addition reactions easily because
a) It has a cyclic structure
b) the double bonds in it are very strong
c) the resonance stabilized system is to be preserved
d) It has six hydrogen atoms.

25) The number of isomers which can be theoretically obtained on monochlorination of 2-methyl-butane is
a) 1
b) 2
c) 3
d) 4.

26) Which of the following reagents can be used to distinguish between propene and propyne ?
a) alone
b) alone
c) Grignard reagent alone
d) Both (b) and (c).

27) <align=”justify”>Which is the most suitable reagent among the following to distinguish compound (3) from rest of the compounds ? <align=”justify”>
1.CH3-C C-CH3

2. CH3-CH2-CH2-CH3

<align=”justify”>3. CH3-CH2-C CH

4. CH3-CH = CH2.

a) Bromine in carbon tetrachloride
b) Bromine in acetic acid
c)
d) Ammoniacal silver nitrate.

28) The presence of unsaturation in organic compounds can be tested with
a)
b)
c)
d)

29) Which of the following shows acidic character ?
a)
b)
c)
d)

30) Aromatic compounds burn with a sooty flame because
a) They have a ring structure of carbon atoms
b) They have a relatively high percentage of hydrogen
c) They have a relatively high percentage of carbon
d) They resist reaction with oxygen of air.

31) Which one of the following will undergo metasubstitution on monochlorination?
a) Ethoxybenzene
b) Chlorobenzene
c) Ethyl benzoate
d) Phenol.

32) Olefins can be hydrogenated by
a) Zinc and hydrochloric acid
b) Raney nickel and hydrogen
c) Nascent hydrogen
d) Lithium aluminium hydride in ether.

33) The most reactive among the following towards sulphonation is
a) Toluene
b) Chlorobenzene
c) Nitrobenzene
d) m-Xylene.

34) A hydrocarbon with the molecular formula C8H18 gives only one monochloro derivative. The hydrocarbon is
a) n-Octane
b) 2-Methylheptane
c) 2, 2, 4-Trimethylpentane
d) 2, 2, 3, 3-Tetramethylbutane.

35) Ozonolysis of 2, 3-dimethyl-1-butene followed by reduction with zinc and water gives
a) Methanoic acid and 3-methyl-2-butanone
b) Methanal and 2-methyl-2-butanone
c) Methanal and 3-methyl-2-butanone
d) Methanoic acid and 2-methyl-2-butanone.

36) Addition of one equivalent of Br2 to 1, 3- pentadiene produces
a) 4, 5-Dibromo-2-pentene
b) 1 , 4-Dibromo-2-pentene
c) 3, 4-Dibromopentene
d) 3, 4-Dibromo-2-pentene.

37) Select the true statement about benzene from amongst the following.
a) Because of unsaturation benzene easily undergoes addition
b) There are two types of C- C bonds in benzene molecule
c) There is cyclic delocalisation of pi-electrons in benzene
d) Monosubstitutioh of benzene gives three isomeric products.

38) Which of the following is not a meta-directing group ?
a)
b)
c) CN
d)

39) Which equation represents an example of the Friedel-Crafts reaction ?
a)
b)
c)
d)

40) Reduction of 2-butyne with sodium in liquid ammonia gives predominantly :
a) cis-2-Butene
b) No reaction
c) trans-2-Butene
d) n-Butane.

41) Which of the following can distinguish propyne from propene?
a)
b)
c)
d)

42) When acetylene reacts with water in the presence of HgSO4, the compound actually isolated is
a)
b)
c)
d)

43) A compound is treated with NaNH2 to give a sodium salt. Identify the compound.
a)
b)
c)
d)

44) The reactivities of the hydrogen atoms attached to different carbon atoms in alkanes which lead to the formation of the carbonium ion of a free radical has the order
a) Tertiary > Primary > Secondary
b) Primary > Secondary > Tertiary
c) Both (a) and (b)
d) Tertiary > Secondary > Primary.

45) What is the decreasing order of strength of the bases:
OH, NH, HC C and CH3CH?

a)
b)
c)
d)

46) Which of the following compounds has the lowest boiling point ?
a)
b)
c)
d)

47) Markovnikovs rule is applicable to
a)
b)
c)
d)

48) An example of an electrophilic substitution reaction is the
a) Chlorination of methane
b) Conversion of methyl chloride to methyl alcohol
c) Nitration of benzene
d) Formation of ethylene from ethyl alcohol.

49) The hydrocarbon which decolourises alkaline KMnO4 solution, but does not give any precipitate with ammonical silver nitrate is
a) Benzene
b) Acetylene
c) Propyne
d) Butyne-2.

50) 2.8g of pure alkene containing only one double bond per molecule, reacts completely with 8 g of bromine (in an inert solvent). What is the molecular formula of the alkene ?
a)
b)
c)
d)

51) The compound X (C5H8) reacts with ammoniacal AgNO3 to give a white precipitate, and on oxidation with hot alkaline KMnO4 gives the acid, (CH3)2CHCOOH. Therefore, X is
a)
b)
c)
d)

52) 1-Butyne on oxidation with hot alkaline KMnO4 would yield
a)
b) , but no CO2
c)
d)

53) When CH3CI and AICI3 are used in Friedel-Crafts reaction, the electrophile is equivalent to:
a)
b)
c)
d)

54) Which of the following is the most reactive towards ring nitration ?
a) Benzene
b) Mesitylene
c) Toluene
d) m-Xylene.

55) Benzene on treatment with a mixture of conc. HNO3 and conc. H2SO4 at 100°C gives
a) Nitrobenzene
b) m-Dinitrobenzene
c) p-Dinitrobenzene
d) o-Dinitrobenzene.

56) In the free radical chlorination of methane, the chain initiating step involves the formation of
a) A chlorine atom
b) Hydrogen chloride
c) Methyl radical
d) Chloromethyl radical.

57) Which of the following does not give a white precipitate with AgNO3 solution ?
a) Propyne
b) 1-Butyne
c) 2-Butyne
d) 1-Pentyne.

58) Which one of the following gives a precipitate with Tollens reagent ?
a) 1-Butanol
b) 2-Butanol
c) 1-Butyne
d) 2-Butyne.

59) Baeyers reagent is
a)
b)
c)
d)

60) Complete combustion of CH4 gives
a)
b)
c)
d)

61) Which of the following metal powders is used to convert trichloromethane into acetylene by heating the latter with it ?
a) Na
b) Mg
c) Ca
d) Ag

62) When an alkyne, RC CH, is treated with cuprous ion in an ammoniacal medium, one of the products is
a)
b)
c)
d)

63) When propene is treated with HBr in the dark and in the absence of peroxide, the main product is
a) 1-Bromopropane
b) 2-Bromopropane
c) 1,2-Dibromopropane
d) 1, 3-Dibromopropane

64) In which of the following is hydrogen most acidic ?
a) Acetylene
b) Methane
c) Ethane .
d) Ethylene.

65) The product formed on passing ethylene through a cold alkaline KMnO4 solution is
a) Ethyl alcohol
b) Ethylene glycol
c) Ethylene oxide
d) Ethane.

66) Which of the following isomers will have the highest boiling point ?

a)
b)
c)
d)

67) Among the following compounds (I — III), the correct order in reaction with electrophile is

a) II>III>I
b) III <i<ii< font=””>
c) I>II>III
d) I = II > III.

68) 1-Butyne reacts with cold alkaline KMnO4 to produce
a) + HCHO
b)
c)
d)

69) In the reaction of C6H5Y, the major product (> 60%) is an m-isomer, so the group Y is
a) -COOH
b)
c) -OH
d) -Cl.

70) 3-Hexyne reacts with Na/liq. NH3 to produce
a) cis-3-Hexen
b) trans-3-Hexene
c) 3-Hexylamine
d) 2-Hexylamine.

71) The most suitable catalyst for the hydrogenation of 2-hexyne –> 2-cis-hexene is
a)
b)
c) 10% Pd – C
d) Raney Ni.

72) The intermediate during the addition of HCI to propene in the absence of peroxide is
a)
b)
c)
d)

73) Benzene + Ozone Y, Y is
a) Benzene monoozonide
b) Benzene diozonide
c) Benzene triozonide
d) All the above.

74) CH3-CH = CH2 + HI X, X is
a)
b)
c)
d) None.

75) A group which deactivates the benzene ring towards electrophilic substitution but which directs the incoming group principally to the o- and p-position is
a)
b) -Cl
c)
d)

76) Which species represents the electrophile in aromatic nitration ?
a)
b)
c)
d)

77) The addition of HI to the double bond of propene yields isopropyl iodide and not n-propyl iodide as the major product, because addition proceeds through
a) a more stable carbonium ion
b) a more stable carbanion
c) a more stable free radical
d) homolysis

78) Which of the following deactivates benzene towards further substitution reaction ?
a) -NHR
b) -OH
c) -COOR
d) -OR.

79) The function of AICI3 in the Friedel-Crafts reaction is
a) to absorb water
b) to absorb HCI
c) to produce an electrophile
d) to produce a nucleophile.

80) Ethylene reacts with 1% cold alkaline KMnO4 to form
a) Oxalic acid
b) Ethylene glycol
c) Ethyl alcohol
d) HCHO.

81) The reaction, Benzene + Methyl halide Toluene is known as the
a) Kolbe reaction
b) Wurtz reaction
c) Perkin reaction
d) Friedel-Crafts reaction.

82) The most reactive compound for electrophilic nitration is
a) Benzene
b) Nitrobenzene
c) Benzoic acid
d) Toluene.

83) The conversion of CICH=CH-CI to CI2CH-CHCI2 can be carried out with
a) alone
b)
c)
d)

84) 1,2-Dibromopropane on treatment with X moles of NaNH2 followed by treatment with ethyl
bromide gave a pentyne. The value of X is

a) One
b) Two
c) Three
d) Four.

85) The order of activity of the given o- and p- directors is
a)
b)
c)
d)

86) Which one of the following compounds will react with methylmagnesium iodide ?
a)
b)
c)
d)

87) Two organic compounds A and B both containing only carbon and hydrogen, on quantitative analysis gave the same percentage composition by weight:
C = (12/13) x 100%. H = (1/13) x 100% A decolourises bromine water but B does not. A and B are respectively

a)
b)
c)
d)

88) Which of the following applies in the reaction,
(i) CH3CH = CHCH3 (major product) (ii) CH2 = CH-CH2CH3 (minor product)

a)
b)
c) Kharasch effect
d)

89) Ozonolysis of C7H14 gave 2-methyl-3-pen- tanone. The alkene is
a) 2-ethyl-3-methyl-1-butene
b) 3-ethyl-2-methyi-3-butene
c) 2, 5-dimethyl-3, 4-dimethylhex-3-ene
d) 3-ethyl-2-methy 1-1 -butene.

90) n-Butylbenzene on oxidation will give
a) benzoic acid
b) butanoic acid
c) benzyl alcohol
d) benzaldehyde

91) An alkane C7H16 is produced by the reaction of lithium di (3-pentyl) cuprate with ethyl bromide. The structural formula of the product is
a) 3-ethylpentane
b) 2-ethylpentane
c) 3-methylhexane
d) 2-methylhexane

92) When cyclohexane is poured on water, it floats, because
a) Cyclohexane is in ‘boat’ form
b) Cyclohexane is in ‘crown’ form
c) Cyclohexane is in ‘chair’ form
d) Cyclohexane is less dense than water.

93) Which of the following has the highest melting point ?
a) n-Pentane
b) Isopentane
c) Neopentane
d) Cyclopentane.

94) Which of the following has the highest dipole moment ?
a) cis-1,2-Dichloroethene
b) cis-1, 2-Dibromo-1, 2-dichloroethene
c) cis-2, 3-Dichloro-2-butene
d) cis-1, 2-Dibromoethene.

95) A cylinder of compressed gas that bears no label is supposed to contain either ethylene or propylene. Combustion of the sample shows that 12cm3 of the gas required 54cm3 of oxygen for complete combustion. This indicates that the gas is
a) Only ethylene
b) Only propylene
c) 1 :1 mixture of the two gases
d) Some unknown mixture of the two gases.

96) Pick out the correct statement.
a) The end products of combustion of paraffins are carboxylic acids
b) Cyclopropane is a better fuel than propane
c) Paraffins are insoluble in benzene
d) The density of paraffins is higher than that of water

97) @ Identify Z in the following reaction sequence :
CH3CH2CH2OH X Y Z
                            160-180°

a)
b)
c)
d)

98) The substance that would not be formed during the reaction of methane and chlorine in the presence of diffused sunlight is
a)
b)
c)
d)

99) The addition of Br2 to cis-2-Butene gives
a) (+)-2, 3-Dibromobutane only
b) (-)-2, 3-Dibromobutane only
c)
d) meso-2, 3-Dibromobutane.

100) Toluene reacts with methyl chloride in the presence of anhydrous aluminium chloride to give mainly m-xylene. This is because
a)
b)
c) because of the hyperconjugation effect of the CH3 group
d) m-xylene is thermodynamically more stable.


Answer

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