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NEET Chemistry MCQ
Hydrocarbons Mcq Neet Chemistry
Quiz 7
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Q.1
on Q183) This reaction is called as ...[BVP 2006]
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a) Fischer-Siper reaction
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b) Clemmensen reduction
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c) Birch reduction
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d) Arndt -Eistert synthesis
Explanation
A terminal double bond may be reduced by Na/NH3(l) in presence of an alcohol and this reduction is called Birch reduction Answer:(c)
Q.2
Which of the following explains why propene undergoes electrophilic addition with HBr, but not with HCN?
0%
a) Br- is better nucleophile than CN-
0%
b) The C-Br bond is stronger than C-CN
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c) HCN reacts preferablly via the lone pair of electron
0%
d) HBr is a stronger acid than HCN and hence is a better souce of protons
Explanation
Hbr being stronger acid tyhan HCN suppiles proton tp proene to form carbocation which then reacts with Br- ion togive 2-bromopropane Answer:(d)
Q.3
Octane number is zerop for ..[ CET Karnataka 2002]
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a) iso-heptane
0%
b) n-heptane
0%
c) iso-octane
0%
d) n-octane
Explanation
Answer:(b)
Q.4
Ozonolysis of 2,3-dimethyl-1-butene followed by reduction with zinc and water gives ..[ IIT 1992]
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a) Methanoic acid and 3-methyl-2-butanone
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b) Methanal and 2-methl-2-butanone
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c) Methanal and 3-methyl-2-butanone
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d) Methanoic acid and 2-methyl-2-butanone
Explanation
Answer:(c)
Q.5
on Q187) In the following reaction the major product 'X' is ...[ AMU 2010]
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a)
0%
b)
0%
c)
0%
d)
Explanation
Answer:(c)
Q.6
According to Huckel rule, an aromatic compound must possess ...[ J & K CET 2007]
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a) (4n + 1) π electrons
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b) (4n + 2) π electrons
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c) (2n+2)π electrons
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d) 4nπ electrons
Explanation
According to Huckel rule, an aromatic compound must possess (4n+2)π electrons Answer:(b)
Q.7
During the preparation of alkanes by Kolbe's electroltic method using inert electrodes, the pH of the electrolyte ...
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a) decreases progressively as the reaction proceeds
0%
b) increases progressively as the reaction proceeds
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c) remains constant througout the reaction
0%
d) may decrease if the concentration of the electrolyte is not very high
Explanation
During the process NaOH is formed Answer:(b)
Q.8
The substituent which is predominantly orth-para directing but deactivating in aromatic electrophilic substitution ...[ Kerala PMT 2010]
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a) - BO2
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b) - cl
0%
c) - OCH3
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d) - CH3
Explanation
- Cl is predominantly ortho-para directing but deactivation in aromatic electrophilic substitution Answer:(b)
Q.9
On electrolysis of potassium succinate solution, the hydrocarbon obtained is ...[ JIPMER 2004]
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a) ethene
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b) ethane
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c) ethyne
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d) all of these
Explanation
Potassium succinate on electrolysis gives ethene Answer:(a)
Q.10
The order of reactivity of following alkenes, when subjected to acid catalyzed hydration is ..[ AMU 2009] I. (CH3)2C = CH2 II. CH3CH = CH2 III. H2C = CH2
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a) I > II > III
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b) I > III > II
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c) III > II > I
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d) II > I > III
Explanation
The order of reactivity of alkenes has been given on the bases of heat of hydrogenation as H2C = CH2 > CH3CH = CH2 > (CH3)2C = CH2 Further the acid catalysed hydration of alkenes afford the formation of carbocation intermediate Answer:(c)
Q.11
Indicate the expected structure of the organic product when ethyl magnesium bromide is treated with heavy water (D2O) ...[ DEC 1994]
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a) C2H5- C2H5
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b) C2H5OD
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c) Sodium nezoate
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d) C2H5D
Explanation
C2H5MgBr + D2O → C2H5D + Mg(OD)Br Answer:(d)
Q.12
Elimination of bromine from 2-bromobutane results in the formation of ...[ JCEC Med. 2008]
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a) equimolar mixture of 1- and 2-butene
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b) predominantly - 2 - butene
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c) predominantly - 1 - butene
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d) predominantly - 2 - butyne
Explanation
Saytzeffs product Answer:(b)
Q.13
The products formed by the action of chlorine on ethane in saturated solution of KBr is/are [ Pb CET 1996]
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a) ClCH2CH2Cl + ClCH2CH2Br
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b) ClCH2CH2Cl
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c) ClCH2CH2Cl + BrCH2CH2Br
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d) ClCH2CH2Cl + BrCH2CH2Br+ ClCH2CH2Br
Explanation
During electrophilic addition of Cl2 to ethene, Cl+ attacks first giving carbocation (I) which is subsequently attacked by either Cl- or Br- giving a mixture of ClCH2CH2Cl and ClCH2CH2Br Answer:(a)
Q.14
Which hydrocarbon is mainly present is gobar gas? [ AFMC 2003]
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a) Butane
0%
b) Propane
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c) Methane
0%
d) Ethane
Explanation
Answer:(c)
Q.15
Which species represents the electrophile in aromatic nitration? [ Pb PMT 1998]
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a) NO2-
0%
b) NO2+
0%
c) NO2
0%
d) NO3-
Explanation
Answer:(b)
Q.16
The compound 1,2-butadiene has ..[ IIT 1983]
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a) only sp-hybridised carbon atoms
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b) only sp2-hybridised carbon atoms
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c) both sp and sp2 -hybridised carbon atoms
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d) sp, sp2 and sp3 -hybridised carbon atoms
Explanation
Structural formula of 1,2-butadiene is Answer:(d)
Q.17
Identify the reagent from the following list which can easily distinguish between 1-butyn and 2-butyne ..[ IIT2002]
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a) bromine, CCl4
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b) H2, Lindlar catalyst
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c) dilute H2SO4, HgSO4
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d) ammonical Cu2Cl2 solution
Explanation
1-butyne is terminal alkyne thus amonical Cu2Cl2 gives red precipitate 2-butyne is non-termical do not give ppt. Answer:(d)
Q.18
on Q199) Following reaction is called
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a) Wurtz's reaction
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b) Kolbe's reaction
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c) Sabatier and Sendern's reaction
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d) Carbylamine reaction
Explanation
Answer:(c)
Q.19
A compound is treated with NaNH2 to give sodium salt. Identify the compound ..[ CBSE PMT 1993]
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a) C2H2
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b) C6H6
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c) C2H6
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d) C2H4
Explanation
Only acetelene have acidic H atom hence gives a salt HC≡CNa Answer:(a)
Q.20
Disubstituted derivatives of benzene are of type/types ...[ BCECE 2005]
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a) 1
0%
b) 2
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c) 3
0%
d) 6
Explanation
Answer:(c)
Q.21
on Q202) In the reaction, the product C is ..... (BHU 1994)
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a) C6H5OH
0%
b) C6H6
0%
c) C6H5COONa
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d) C6H5ONa
Explanation
Answer:(b)
Q.22
Which cycloalkane has the lowest heat of combustion per -CH2 group? [ CET Karnataka 2006]
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a) cyclopropane
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b) cyclobutane
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c) cyclopentane
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d) cyclohexane
Explanation
Cyclohexane has the lowest heat of combustion per -CH2 group (deviation = -5°16') and is found to be quite stable Answer:(d)
Q.23
Ethylene reacts with 1% cold alkaline KMnO4 to form ..[ Hariyana CEET 1998]
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a) Oxalic acid
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b) Ethylene glycol
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c) Ethy alcohol
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d) HCOH
Explanation
Answer:(b)
Q.24
Which of the following reagent distinguish ethylene from acetylene? [ BHU 2006]
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a) Ammoniacal cuprous chloride
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b) Br2 water
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c) Alkaline KMnO4
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d) Chlorine dissolved in CCl4
Explanation
Acetylene on treatment with ammonical cuprous chloride gives a red precipitate of cuprous acetylide Answer:(a)
Q.25
Excess of CH3COOH is reacted with CH ≡ CH in presence of Hg2+, the product is ...[ BHU 1998]
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a) CH3CH(OOCCH3)2
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b) CH2= CH(OCOCH3)
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c) (CH3COO)CH2 - CH2(OOCCH3)
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d) None of these
Explanation
By MArkovnikov's addition Answer:(a)
Q.26
Acidic hydrogen is present in ...[ IIT 1984]
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a) ethyne
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b) ethene
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c) benzene
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d) ethane
Explanation
Terminal alkynes are slightly acidic, forms salt with very strong base like Na, NaNH2 etc Answer:(a)
Q.27
Which of the following possesses the highest melting point ? [ Manipal 2001]
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a) Chlorobenzene
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b) o-dichlorobenzene
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c) m-dichlorobenzene
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d) p-dichlorobenzene
Explanation
p-dichlorobenzene being symmetrical fit closly witheach other hencehas the highest melting point Answer:(d)
Q.28
The compound with highest boiling point is .... [ IIT 1982]
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a) n-Hexane
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b) n-Pentane
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c) 2,2-Dimethylpropane
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d) 2-Methybutane
Explanation
HIgher the number of carbon higher is the boiling point Answer:(a)
Q.29
The reaction of propen with HOCl (Cl2+H2O) proceeds through the intermediate ...[ IIT 2016]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Answer:(a)
Q.30
on Q211) Identify the alkyne in the following sequence of reaction:... [ EAMCET 2009]
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a) H3C - C = C - CH3
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b) H3C - CH2 - C ≡ CH
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c) H2C = CH - C ≡ CH
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d) HC ≡ C - CH2 - C ≡ CH
Explanation
Answer:(a)
0 h : 0 m : 1 s
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