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NEET Chemistry MCQ
Hydrocarbons Mcq Neet Chemistry
Quiz 1
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Q.1
Conversion of CH4 to CH3Cl is an example of .... ... reaction[KCET1998]
0%
a) Electrophilic substitution
0%
b) Nucleophilic substitution
0%
c) Free radical substitution
0%
d) Free radical addition
Explanation
Answer:(c)
Q.2
An alkene "A" on reaction with O3and Zn–H2O gives propanone and ethanal in equimolar ratio. Addition of HCl to alkene "A" gives "B" as the major product. The structure of product "B" is:.... [NEET 2019]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Answer:(c)
Q.3
Which of the following alkane cannot be made in good yield by Wurtz reaction? [NEET 2020]
0%
a) n-Heptane
0%
b) n-Butane
0%
c) n-Hexane
0%
d) 2,3-Dimethylbutane
Explanation
Answer:(a)
Q.4
An alkene on ozonolysis gives methanal as one of the product. Its structure is ... [ NEET 2020 ]
0%
a)
0%
b) Rosenmund reaction
0%
c) Friedel-CCraft reaction
0%
d) Gattermann Hoch reaction
Explanation
Answer:(d)
Q.5
An alkene on ozonolysis gives methanal as one of the product. Its structure is ...[ NEET 2020]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Answer:(a)
Q.6
The number of sigma (σ) and pi (π) bonds in pent-2-en-4-yne is .... [NEET 2018]
0%
a) 10σ bonds and 3π bonds
0%
b) 8σ bonds and 5π bonds
0%
c) 11σ bonds and 2π bonds
0%
d) 13σ bonds and no π bonds
Explanation
Answer:(a)
Q.7
tion Q5) The most suitable reagent for the following conversion, is : .... [NEET 2019]
0%
a) Na/liquid NH3
0%
b) H2, Pd/C, quinoline
0%
c) Zn/HCl
0%
d) Hg2+/H+, H2O
Explanation
Answer:(b)
Q.8
tion Q6) The compound C7H8 undergoes the following reactions : The product ‘C’ is .... [ NEET 2018]
0%
a) 3-bromo-2,4,6-trichlorotoluene
0%
b) o-bromotoluene
0%
c) m-bromotoluene
0%
d) p-bromotoluene
Explanation
Answer:(c)
Q.9
than one correct option Q7) Hydrocarbon (A) reacts with bromine by substitution to form an alkyl bromide which by Wurtz reaction is converted to gaseous hydrocarbon containing less than four carbon atoms. (A) is ... [NEET 2018]
0%
a) CH3 – CH3
0%
b) CH2 = CH2
0%
c) CH ≡ CH
0%
d) CH4
Explanation
Answer:(d)
Q.10
than one correct answer Q9) Electrolysis of potassium acetate gives ..
0%
a) Ethylene
0%
b) Acetylene
0%
c) Ethane
0%
d) Potassium hydroxide
Explanation
On electrolysis of 2CH3COOK → CH3 - CH3 + 2CO2 + H2 + 2KOH Answer:(c, d)
Q.11
ion Q10) Isomers of hexane, based on their branching, can be divided into three distinct classes as shown in figure The correct order of their boiling point is ..[ IIT Adv 2014]
0%
a) I > II > III
0%
b) III > II > I
0%
c) II > III > I
0%
d) III > I > II
Explanation
Boiling popint of isomeric alkanes depends on surface area. More the branching ,lesser will be its surface area and lesser will be the boiling point On moving from III to I branching increases, surface area decreases, boiling point decreases Answer:(b)
Q.12
Which one of the following is not formed when a mixture of methyl bromide and bromobenzene is heated with sodium metal in the presence of dry ether? [ Karnataka CET 2012]
0%
a) Ethane
0%
b) Diphenyl
0%
c) Propane
0%
d) Toluene
Explanation
Propane is not formed in Wurtz reaction because CH3Br gives ethane, C6H5Br gives diphenyl and a mixture of C6H5Br and CH3Br gives toluene Answer:(c)
Q.13
Addition of ICl on pronene gives the product
0%
a) CH3CHCHClCH3
0%
b) CH3CHClCH2Cl
0%
c) CH3CHICH2Cl
0%
d) CH3CHClCH2I
Explanation
In case of addition of interhalogen compounds,the halogen atom with lower electronegativity is assigned partial positive charge whereas hal;ogen atom with comparatively higher electronegativity is assigned partial negative charge. Order of electronegativity of various halogen atoms is F >Cl>Br>>I Answer:(d)
Q.14
Trans-2-butene + Br2 gives ..[ Guj CET 2006]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Answer:(a)
Q.15
Which of the following compounds will forma hydrocarbon on reaction with a Grignard reagent? [ CPMT 1988]
0%
a) CH3CO2CH3
0%
b) CH3CH2OH
0%
c) CH3CHO
0%
d) CH3COCH3
Explanation
A grignard reagent will be decomposed to give the corresponding alkanes when it reacts with alcohol CH3CH2OH + CH3MgBr → CH4 + MgBr(OC2H5) Answer:(b)
Q.16
Methyl bromide is converted into ethane by heating it in ether medium with ...[ CET Karnataka 2006]
0%
a) Al
0%
b) Zn
0%
c) Na
0%
d) Cu
Explanation
2CH3-Br + 2Na → CH3-CH3 The Wurtz reaction is an organic reaction used to couple two alkyl halides to form an alkane using sodium metal. The mechanism begins with a single electron transfer (SET) from sodium metal to the alkyl halide, which dissociates to form an alkyl radical and sodium halide salt. Another molecule of sodium performs another SET to the alkyl radical to form a nucleophilic carbanion. The carbanion then attacks another molecule of alkyl halide in a nucleophilic substitution reaction (SN2) to form the final coupled product and another molecule of sodium halide salt Answer:(c)
Q.17
Consider the following statements: A hydrocarbon of molecular formula C5H10 is a I. monosubstituted alkene II. disubstituted alkene III. trisubstituted alkene Which ofthe following statements are correct?
0%
a) I, II and III
0%
b) I and II
0%
c) II and III
0%
d) I and III
Explanation
A monosubstituted alkene is an alkene in which the doubly bonded carbons are bonded to only one carbon excluding each other. A disubstituted alkene is an alkene in which the doubly bonded carbons are bonded to a total of two carbon atoms. A trisubstituted alkene is an alkene in the molecule of which the doubly bonded carbons are bonded to a total of three carbon atoms excluding each other. A tetrasubstituted alkene is an alkene in the molecule of which the doubly bonded carbons are bonded to a total of four carbon atoms excluding each other. Answer:(a)
Q.18
ion Q17) What will be product when HBr is reacted with
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Electrophilic addition on C= C is governed by stability of carbocation Answer:(c)
Q.19
Thew product obtained when methyl magnesium bromide reacts with methyl alcohol is ..
0%
a) Acetone
0%
b) Alcohol
0%
c) Methane
0%
d) Ethane
Explanation
CH3OH +CH3MgBr → CH4 + Mg(OCH3)Br Answer:(c)
Q.20
Amongst the following compounds which can be most easily sulphonated ... [ IIT 1982]
0%
a) Benzene
0%
b) Nitrobenzene
0%
c) Tolune
0%
d) Chlorobenzene
Explanation
Because of the +I effect of the CH3 group tolunene has thehighest electron density in the benzene ring and hence can be most readily sulphonated Answer:(c)
Q.21
When cyclohexane is poured on water, it floats because ...[ IIT 1997]
0%
a) cyclohexane is in 'boat' form
0%
b) cyclohexane is in 'chair' form
0%
c) cyclohexane is in 'crown' form
0%
d) cyclohexane is less dense than water
Explanation
Alkanes are all less dense than water, floats over water Answer:(d)
Q.22
In the sulphonation of benzene, the electrophilic involved is ...[ Karanataka CET 2009]
0%
a) HSO4-
0%
b) SO3
0%
c) SO2
0%
d) SO42-
Explanation
SO3 (or SO3+H) is the electrophile involved in sulphonation of benzene 2H2SO4 ⇌ H3O+ + HSO4- + SO3 (Electrophile) Answer:(b)
Q.23
Which of the following is the most stable alkene? [ AFMC 2007]
0%
a) R2C = CR2
0%
b) RCH = CHR
0%
c) RCH = CH2
0%
d) H2C = CH2
Explanation
Most substituted alkene is the most stable i.e. R2C = CR2 Answer:(a)
Q.24
eaction of alkenes with halogens is explosivew to case of ..[ Pb CET 1989]
0%
a) F2
0%
b) Cl2
0%
c) Br2
0%
d) I2
Explanation
Answer:(a)
Q.25
In order to get propane gas, which of the following should be subjected to sodalime decarboxylation? [ BVP 2006]
0%
a) Sodium formate
0%
b) Mixture of sodium acetate and sodium ethanoate
0%
c) Sodium butyrate
0%
d) Sodium propionate
Explanation
CH3CH2CH2COOH + 2NaOH + CaO → CH3CH2CH3 + Na2CO3 + Ca(OH)2 Answer:(c)
Q.26
Which of the following is not a meta-directing group? [ CPMT 1992]
0%
a) SO3H
0%
b) NO2
0%
c) CN
0%
d) NH2
Explanation
Answer:(d)
Q.27
ion Q27) [IIT 2003]
0%
a)
0%
b)
0%
c)
0%
d)
Explanation
Reaction proceeds through carbocation intermediate Answer:(a)
Q.28
Photochemical chlorination of alkane is initiated by a process of ...
0%
a) Pyrolysis
0%
b) Substitution
0%
c) Homolysis
0%
d) Peroxidation
Explanation
In photochemical chlorination, the first step is generation of free radical by homolysis Cl - Cl → Cl. + Cl. Answer:(c)
Q.29
Acidic hrdrogen is present in ... [ AFMC 1999]
0%
a) Ethyne
0%
b) Ethene
0%
c) Benzene
0%
d) Ethane
Explanation
Any H attached to an electronegative atom can behave as acidic hydrogen. In addition to that, we can use following general rule: Acidic Strength: Alkane < alkene < NH3 < Alkyne < alcohol < Water < Phenol < Nitrophenol
Q.30
Which of the following compound does not dissolve in conc. H2SO4 even on worming? ..[ IIT 1983]
0%
a) Ethylene
0%
b) Benzene
0%
c) Hexane
0%
d) Aniline
Explanation
Ethylene absorb H2SO4 forming CH3 - CH2OSO3H and dissolve, Benzene, with warm H2SO4, undergo sulphonation and dissolve. Hexane, a hydrophobic molecule, does not react with H2SO4 remains insoluble Answer:(c)
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