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NEET Chemistry MCQ
Hydrocarbons Mcq Neet Chemistry
Quiz 10
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Q.1
The hydrocarbon which does not decolourise alkaline KMnO4 solution and also does not give any precipitate with ammoniacal silver nitrate is ...[ AIIMS 2007]
0%
a) benzene
0%
b) acetylene
0%
c) propyne
0%
d) 1-butyne
Explanation
As benzene is resonance stabilized so, it does not decolourised alkaline KMnO4 solution and also does not give any precipitate with ammoniacal AgNO3 solution ( as it has no acidic H-atom) Answer:(a)
Q.2
In methyl alcohol solution bromine reacts with ethylene to yield BrCH2CH2OCH2 in addition to 1,2-dibromoethane because ..[ Pb CEET1998]
0%
a) this is a free radical mechanism
0%
b) the methyl alcohol sollvates the bromine
0%
c) the ion formed initially may react with Br- or CH3OH
0%
d) the methyl alcohol solvates the bromine
Explanation
Ethylene reacts with Br+ to give ion ion reacts with Br- and CH3OH to give BrCH2CH2Br and BrCH2CH2OCH3 respectively Answer:(c)
Q.3
Both methane and ethane may be obtained by a suitable one step reaction from [ BHU 2004]
0%
a) CH3I
0%
b) CH2CH2I
0%
c) CH3OH
0%
d) C2H5OH
Explanation
Answer:(a)
Q.4
Acetylene when reacts with two molecules of HBr then it gives
0%
a) Br-C≡C-Br
0%
b) Br-CH=CH-Br
0%
c) Br2C-CBr2
0%
d) CH3-CHBr2
Explanation
Answer:(d)
Q.5
onPassage Based Questions Q277) An acyclic hydrocarbon P, having molecular formula gave acetone as the organic product through the following sequence of reactions, in which Q is an intermediate organic compound ...[IIT 2011] The structure of the compound Q is
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Answer:(b)
Q.6
n presence of peroxid, hydrogen chloride and hydrogen iodide do not give anti-Markovnikov's addition to alkenes because ..[ IIT2001]
0%
a) both are highly ionic
0%
b) one is oxidising and the other is reducing
0%
c) one of the steps is endothermic in both the cases
0%
d) all the steps are exothermic in both the cases
Explanation
reaction of Hcl with carbon radical of alkenes is endothermic and reaction of HI with double bond in alkene is endothermic Answer:(c)
Q.7
When CH3Cl and AlCl3 are used in Friedel-Crafs reaction, the electrophile is ...[ CBSE PMT 1994]
0%
a) Cl+
0%
b) AlCl4-
0%
c) CH3+
0%
d) AlCl2+
Explanation
Answer:(c)
Q.8
Cyclohexene is best prepared from cyclohexanol by which of the following? [ IIT 2005]
0%
a) conc H3PO4
0%
b) conc HCl/ ZnCl2
0%
c) conc. HCl
0%
d) conc. HBr
Explanation
Cyclohexanol on treatment with concentrated H3PO4 undergo acid catalysed dehydration giving cyclohexene Answer:(a)
Q.9
Which is most reactive towards electrophilic reagent? [ AIPMT 2010]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
is more reactive towards electrophilic reagents. The reason for this is the presence of -CH3 group (due to +I effect) and -OH group (by its resonance (R) effect) which increases the electron density on the benzene ring Answer:(a)
Q.10
In preparation of alkene from alcohol using Al2O3 which is an effective factor? [ CBSEPMT 2001]
0%
a) Temperature
0%
b) Concentration
0%
c) Porosityof Al2O3
0%
d) Surface area of Al2O3
Explanation
Answer:(c)
Q.11
on Q283) In the reactions (A) and (B) are geometrical isomers. Then ... [ EAMCET Med. 2007]
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a) A is cis and B is trans
0%
b) A is trans and B is cis
0%
c) A and B are cis
0%
d) A and B are trans
Explanation
Answer:(b)
Q.12
Octane number can be changed by ...[ AFMC 2004]
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a) isomerissation
0%
b) alkylation
0%
c) cyclisation
0%
d) all of these
Explanation
Answer:(d)
Q.13
on Q285) Products of the following reaction [ AMU 2009]
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a) Me2CO + CH3CHO
0%
b) CH3CHO + CH3COOH
0%
c) Me2CO + CH3COOH
0%
d) 2Me2CO
Explanation
Answer:(a)
Q.14
What is the type of reaction CH2 = CHCH3 + HBr → CH3CHBrCH3 ..[ AFMC1999]
0%
a) Nucleophilic addition reaction
0%
b) Free radical addition reaction
0%
c) Electrophilic substitution reaction
0%
d) Electrophilic addition reaction
Explanation
it is electrophilic addition reaction Answer:(d)
Q.15
Addition of HI to double bond of propene yields isopropyl iodide and not n-propyl iodide as the major product, because addition proceeds through ...[ Haryana CEET 1998]
0%
a) a more stable carbonium ion
0%
b) a more stable carbanion
0%
c) a more stable free radical
0%
d) homolysis
Explanation
Addition proceeds through more stable carbonium ion Answer:(a)
Q.16
The correct order of reactivity towards electrophilic substitution is
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a) phenol > benzene > chlorobenzene > benzoic acid
0%
b) benzoic acid > chlorobenzene > benzene > phenol
0%
c) phenol > chlorobenzene > benzene > benzoic acid
0%
d) benzoic acid > phenol > benzene > chlorobenzene
Explanation
Electrone releasing groups activate and electron withdrawing groups deactivate the benzene ring towards electrophilic substitutions. Thus order of reactivity is phenol > benzene > chlorobenzene > benzoic acid Answer:(a)
Q.17
Two gases, P and Q decolourises aqueous bromide but only one of them gives white precipitate with aqueous ammonical silver nitrate solution. P and Q are likely to be ... [ DEC 1994]
0%
a) Ethane and ethyne
0%
b) But-1-yne and but-2-yne
0%
c) Ethane and but-2-yne
0%
d) Ethyne and popyne
Explanation
Both gases are unsaturated hydrocarban Only non-terminal alyne to dont give any precipitate with ammonical silver nitrate, Answer:(b)
Q.18
on Q290) The number of optically active products obtained from the complete ozonolysis of the given compound is ...[ IIT 2012]
0%
a) 0
0%
b) 1
0%
c) 2
0%
d) 4
Explanation
Since, none of the above dial is chiral, no optically active product is obtained Answer:(a)
Q.19
on Q291) In the following reaction, the product 'R' is [ AFMC 2010]
0%
a) benzene
0%
b) ethylbenzene
0%
c) toluene
0%
d) n-propyl benzene
Explanation
Answer:(c)
Q.20
Pure methane can be produced by ... [ DEC 2001]
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a) Wurtz reaction
0%
b) Kolbe's electrolysis method
0%
c) Soda-lime decarboxylation
0%
d) Reduction with H2
Explanation
Answer:(c)
Q.21
Which of the following reagents, when heated withethyl chloride, forms ethylene? [ AFMC 2008]
0%
a) Aqueous KOH
0%
b) Zn/HCl
0%
c) Alcohol KOH
0%
d) HI
Explanation
Answer:(c)
Q.22
Which of the following will be most easily attacked by an electrophile..[CBSE PMT 1999]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Both -OH and -CH3 are electrondonating group but stengthof -OH is more thanCH3 group.Thus electron density is much higher in phenol compared with other Answer:(c)
Q.23
Chloroform or iodoform on heating with silver powder gives ..[ CET J&K 2011]
0%
a) CH4
0%
b) C2H4
0%
c) C2H6
0%
d) C2H2
Explanation
CHX3 + 6Ag + X3HC → HC≡CH + 6AgX Answer:(d)
Q.24
Tolune reactswith methyl chloride in presence of anhydrous aluminium chloride to give mainly m-xylene. This is because
0%
a) CH3-group is m-directing
0%
b) CH3-group has +I effect
0%
c) because of hyperconjugation effect of the CH3-group
0%
d) m-xylene isthermodynamically more stableInitially formed o- and p-xylenes under the reaction condition are converted into thermodynamically morestable m-xylene
Explanation
Answer:(d)
Q.25
ion and Reason Q297) Statement I : Addition of bromine to trans-2-butene yields meso-2,3-dibromobutane. Statement II : Bromine addition to an alkene is an electrophilic addition
0%
a) Statement I is correct Statement II is correct Satement II is a correct explanation of statement I
0%
b) Statement I is correct statement II is correct statement II is not the correct explanation of statement I
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c) Statement I is correct, statement II is incorrect
0%
d) Statement I is incorrect statement II is correct
Explanation
Answer:(b)
Q.26
Decarboxylation of isobutyric acid leads to ...
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a) Iso - Butane
0%
b) Propane
0%
c) Butane
0%
d) None of these
Explanation
Answer:(b)
Q.27
The hydrocarbon which decolourises alkaline KMnO4 solution, but does not give any precipitate with ammonical silver nitrate is ...[ AIIMS 1994]
0%
a) Benzene
0%
b) Acetylene
0%
c) Propyne
0%
d) Butyne-2
Explanation
Only non-terminal alyne to dont give any precipitate with ammonical silver nitrate, Butyne-2 is non-terminal alyne in given option Answer:(d)
Q.28
Which compound would give 5-keta-2-methyl hexanal upon ozonilysis? [ IIT 2015]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Answer:(b)
Q.29
Reaction of HBr with propene in absence of peroxide is a/an ...[ Kerala PMT 2011]
0%
a) electrophilic addition
0%
b) electrophilic substitution
0%
c) nucleophilic substitution
0%
d) free radical addition
Explanation
Addition of HBr to propene is an electrophilic addition reaction, in which the electrophilic is H+ Answer:(a)
Q.30
In the free radical chlorination of methane, the chain initiation step involves the formation ...[ CBSE PMT 1994]
0%
a) Chlorine atom
0%
b) Hydrogen chloride
0%
c) Methyl radical
0%
d) Chloromethyl radical
Explanation
Answer:(a)
0 h : 0 m : 1 s
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