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Hydrocarbons Mcq Neet Chemistry
Quiz 8
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Q.1
Mono sodium acetylide reacts with an alkyl halide to form ...[ BHU 1994]
0%
a) An alkane
0%
b) An alkene
0%
c) An unsymmetric higher alkyne
0%
d) A symmmetric higher alyne
Explanation
HC ≡ CNa + RX → HC ≡ C - R + NaX An unsymmetrical higher alkyne Answer:(c)
Q.2
Which of the following gives propyne on hydrolysis? [ AIIMS 2005]
0%
a) Al4C3
0%
b) Mg2C3
0%
c) B4C
0%
d) La4C3
Explanation
Mg2C3 + 4H2O → CH3 - C ≡CH + 2Mg(OH)2 Answer:(b)
Q.3
Ethyne can be oxidised to oxalic acid by using ...[ AMU 1998]
0%
a) Chromic acid
0%
b) Alkaline KMnO4
0%
c) Hypochlorous acid
0%
d) All reagents
Explanation
Answer:(b)
Q.4
The negative part of the addendum adds on to the unsaturated carbon atom joined to the least number of hydrogen atoms. This statement is called ...[ AFMC 2004]
0%
a) Saytzeff rule
0%
b) Kharasch effect
0%
c) Markownikoff's rule
0%
d) Anti-Saytzeff rule
Explanation
According to markownikoff's rule the negative part of the addendum adds on to the unsaturated carbon atom joined to the least number of hydrogen atoms Answer:(c)
Q.5
In the reaction of C6H5Y, the major product (> 60%) is m- isomers, so the group Y is ...[ AIIMS 1997]
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a) -COOH
0%
b) -NH2
0%
c) -OH
0%
d) -Cl
Explanation
Y must be meta directing from given options only -COOH group is metadirecting Answer:(a)
Q.6
Which one of the following alkenes will react faster with H2 under catalytic hydrogenation condition? [ IIT 2000 ]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Ease of catalytic hydrogenation depends upon the size of groups present at the doubly bonded carbon. Larger the size of groups, difficult the hydrogenation. Therefore, in the given situation, disubstituted reacts at faster rate than tri and tera substituted alkene. Among disubstituted, the stability order is cis < geminal < trans Answer:(a)
Q.7
The ortho/para directing group among the following is ...[ AIIMS 2003]
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a) COOH
0%
b) CN
0%
c) COCH3
0%
d) NHCOCH3
Explanation
NHCOCH3 is o- and p- directing while others are m-directing Answer:(d)
Q.8
Benzene can not undergo
0%
a) elemeniation
0%
b) substitution
0%
c) addition
0%
d) oxidation
Explanation
Answer:(a)
Q.9
han one correct answer Q220) Using anhydrous AlCl3 as catalyst, which of the following reactions produces ethylbenzene (PhEt)? [ AIPMT 2004]
0%
a) CH3CH2OH + C6H6
0%
b) CH3CH=CH2 + C6H6
0%
c) H2C = CH2 + C6H6.
0%
d) H2C = CH2 + C6H6
Explanation
Answer:(a, c)
Q.10
on Q221) In a set of reaction, ethylbenzene yielded a product (D) ..[ AIPMT 2010]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Answer:(d)
Q.11
Which of the following heptanols can be dehydrated to hept-3-ene only ..
0%
a) Heptan-3-ol
0%
b) Heptan-4-ol
0%
c) Heptan-2-ol
0%
d) Heptan-1-ol
Explanation
Answer:(b)
Q.12
Which of the following alkenes will give an optically active alcohol when treated with H2O/ H2SO4 [ CPMT 2004]
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a) 1-Butene
0%
b) Ethene
0%
c) Propene
0%
d) 2-Methyl propene
Explanation
Answer:(a)
Q.13
When cyclohexane is poured on water, it floats because ...[ IIT 1997]
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a) Cyclohexane is in 'boat' form
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b) Cyclohexane is in 'chair' form
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c) Cyclohexane is in 'crown' form
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d) Cyclohexane is less denser than water
Explanation
Answer:(d)
Q.14
Which of the following will decolourise alkaline KMnO4 solution [ IIT 1998]
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a) C3H8
0%
b) CH4
0%
c) CCl4
0%
d) C2H4
Explanation
Unsaturated compounds which contain C=C or C≡C decolourises the purple colour of alkaline KMnO4 solution Answer:(d)
Q.15
oftrhe following statements is/are incorrect
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a) Bromination of p-nitrotoluene in presence of iron gives 2-bromo-4nitrotoluene
0%
b) Sul;phonation of p-tert-butyltolune gives 5-tert-butyl-2-methyl-1-benzenesulphonicacvid
0%
c) Nitration of m-xylens gives 2,4-dimethyl-1-nitrobenzene
0%
d) Friedel-Crafts reaction of benzene with sec-butyl bromide predominantly gives isobutyl-benzene
Explanation
Only statement (d)is incorrect as itgives secbutylbenzene Answer:(d)
Q.16
Which one of the following compound does not dissolve in conc. H2SO4, even on worming?
0%
a) Aniline
0%
b) Benzene
0%
c) Hexane
0%
d) Ethylene
Explanation
Exect Hexene other gets sulfonated Answer:(c)
Q.17
The synthesis of 3-octyne is achived by adding a bromoalkane into a mixture of sodium amide and an alyne. The bromoalkane and lakyne respectively are ... [ IIT 2010]
0%
a) BrCH2CH2CH2CH2CH3 and CH3CH2C ≡ CH
0%
b) BrCH2CH2CH3 and CH3CH2CH2C≡CH
0%
c) BrCH2CH2CH2CH2CH3 and CH3C ≡ CH
0%
d) BrCH2CH2CH2CH3 and CH3CH2C≡CH
Explanation
Answer:(d)
Q.18
The carbon-carbon bond order in benzene is ...[ BCECE 2008]
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a) 1
0%
b) between 1 and 2
0%
c) 1.5
0%
d) 2
Explanation
The C - C bond order in benzene is between 1 and 2 Answer:(b)
Q.19
For preparing an alkane, a concentrated solution of sodium or potassium salt of saturated carboxylic acid is subjected to ...[ MPPMT 1999]
0%
a) hydrolysis
0%
b) oxidation
0%
c) hydrogenation
0%
d) electrolysis
Explanation
Answer:(d)
Q.20
on Q233) Following compound is an ...[DPMT 2007]
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a) alkyne, 3°amine
0%
b) alkene, 2°amine
0%
c) alkene, 3°amine
0%
d) alkyne, 2°amine
Explanation
Answer:(c)
Q.21
The most suitable catalyst for the hydrogenation of 2-heyne → cis-hexene is
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a) Pb-BaSO4
0%
b) (Ph3P)3RhCl
0%
c) 10%Pd-C
0%
d) Raney Ni
Explanation
Pb-BaSO4 is Lindlar's catalyst, gives cis-hexene on reduction of 2-heyne Answer:(a)
Q.22
An alkane with a molecular formula. C6H14 reacts with chlorine in the presence of light and heat to give two constitutionally isomeric monochlorides of molecular formula, C6H13Cl. What is the most reasonable starting alkane? [ CET |(J&K) 2011]
0%
a) n-Hexane
0%
b) 2,2-Dimentylbutane
0%
c) 2,3-Dimethylbutane
0%
d) 3-Methylpentane
Explanation
Answer:(c)
Q.23
on Q236)Among the following compounds, the decreasing order of reactivity towards electrophilic substitutiuon is ...[CBSE PMT 2000 ]
0%
a) III > I > II > IV
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b) IV > I > II > III
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c) I > II > III > IV
0%
d) II > I > III > IV
Explanation
OCH3 is a strong electon donating group followed by CH3 while CF3 is strong electron withdrawing group.. Reaactivity of electrophilic substitutiuon depends on electron donating group Answer:(a)
Q.24
The product(s) obtained via oxymercuration (HgSO4 + H2SO4) of 1-butyne would be ...[ IIT 1999]
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a) CH3 - CH2 - CO - CH3
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b) CH3 - CH2 - CH2 - CHO
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c) CH3 - CH2 - CHO + HCHO
0%
d) CH3 - CH2 - COOH + HCOOH
Explanation
Oxymercuration - demercuration brings about Markownikoff's addition of water as Answer:(a)
Q.25
The reaction, Benzene + Methyl halide → Tolune in presence of Anhyd. (AlCl3), is kown as .. [ AIIMSS 1998]
0%
a) Kolbe reaction
0%
b) Wurtz reaction
0%
c) Perkin reaction
0%
d) Friedel-Craft reaction
Explanation
Answer:(d)
Q.26
What is the decreasing order of strength of bases OH-, NH2-, HC ≡C- and CH3CH2-? [ IIT 1993]
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a) CH3CH2- > NH2- > HC ≡C- > OH-
0%
b) HC≡ C- > CH3CH2- >NH2- > OH-
0%
c) OH- > NH2- > HC ≡C-> CH3CH2-
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d) NH2- > HC ≡ C- > OH- > CH3CH2-
Explanation
Stronger the acid, weaker the conjugated base, since the acid character decreases in the order H2O > NH3 > HC ≡ CH > CH3 - CH3, therefore, the basic character of their conjugate bases decreases in reverse order Answer:(a)
Q.27
1-bromo-3-chlorocyclobutane when treated with two equivalents of Na, in the presence of ether which of the following will be formed? [ IIT 2005]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Answer:(d)
Q.28
The compound that is most reactive towards electrophilic nitration is ...[ AIPMT 2012]
0%
a) toluene
0%
b) benzene
0%
c) nitrobenzene
0%
d) benzoic acid
Explanation
As the electron donating CH3 group (+I effect) increases reactivity towards electrophilic substitution (nitration) therefore toluene is most reactive. Answer:(a)
Q.29
Heating a mixture of sodium benzoate or benzoic acid and soda-lime gives ...[ AFMC 1999]
0%
a) Benzene
0%
b) Methane
0%
c) Sodium benzoate
0%
d) Calcium benzoate
Explanation
benzene can be made by heating soda lime with solid benzoic acid (benzenecarboxylic acid), C6H5COOH. Answer:(a)
Q.30
Which of the following reactions will yield 2,2-dibromo-propane? [ CEPMT 2004]
0%
a) H2C = CHBr + HBr
0%
b) CH3C ≡ CCH3 + 2HBr
0%
c) CH3C ≡ CH + 2HBr
0%
d) CH3CH = CHBr + HBr
Explanation
Answer:(c)
0 h : 0 m : 1 s
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