JEE Chemistry Hydrocarbons MCQs Set B

Question: Which one of the following is the strongest bond?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:   An alkyne has general formula

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question:

• a) Pent-4-yn-2-ene
• b) Pent-2-en-4-yne
• c) Pent-l-yn-3-ene
• d) Pent-3-en-1-yne

Answer: Pent-4-yn-2-ene

Question: Number of alkynes for formula C₅H₈ is –

• a) 3
• b) 5
• c) 2
• d) 4

Answer: 3

Question:

• a) 1-butene-3-yne
• b) 1-butyn-3-ene
• c) but-1-yne-3-ene
• d) 3-butene-1-yne

Answer: 1-butene-3-yne

Question: The homologue of ethyne is

• a) C₃H₆
• b) C₂H₆
• c) C₂H₄
• d) None of these

Answer: C₃H₆

Question: The C - H bond length is minimum in the bond formed by

• a) sp - s overlapping (as in alkynes)
• b) sp² – s overlapping (as in alkenes)
• c) sp³ – s overlapping (as in alkanes)
• d) None of these

Answer: sp - s overlapping (as in alkynes)

Question: Triple bond of ethyne is made of

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Maximum carbon-carbon bond distance is found in –

• a) ethane
• b) ethyne
• c) ethene
• d) benzene

Answer: ethane

Question: The acetylene molecule contains

• a) 3 sigma and 2 pi bonds
• b) 5 sigma bonds
• c) 4 sigma and 1 pi bonds
• d) 2 sigma and 3 pi bonds

Answer: 3 sigma and 2 pi bonds

Question: Butyne-2 contains

• a) both sp and sp³ hybridised carbon atoms
• b) both sp and sp² hybridised carbon atoms
• c) sp³ hybridised carbon atoms only
• d) sp hybridised carbon atoms only

Answer: both sp and sp³ hybridised carbon atoms

Question: The correct order towards bond length is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) I
• b) II
• c) III
• d) all are equal electronegative

Answer: I

Question:

• a) KOH in C₂H₅OH
• b) Na
• c) HCl in H₂O
• d) Zn in alcohol

Answer: KOH in C₂H₅OH

Question: Calcium carbide when treated with water gives

• a) acetylene
• b) ethylene
• c) methane
• d) ethane

Answer: acetylene

Question: Which one of the following has the minimum boiling point ?

• a) Isobutane
• b) 1-Butyne
• c) 1-Butene
• d) n- Butane

Answer: Isobutane

Question: Ammonical silver nitrate forms a white precipitate easily with

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: When acetylene is passed through dil. H₂SO₄ in presence of HgSO₄, the compound formed is

• a) acetaldehyde
• b) ketone
• c) ether
• d) acetic acid

Answer: acetaldehyde

Question: Which of the following will be the final product when C₂H₂ reacts with HCl

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: The hydrocarbon which can react with sodium in liquid ammonia is

• a) 

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  Which of these will not react with acetylene?

• a) NaOH
• b) Na
• c) Ammonical AgNO₃
• d) HCl.

Answer: NaOH

Question: When acetylene is passed over heated iron tube, the product obtained is –

• a) C₆H₆
• b) C₂H₂
• c) C₄H₄
• d) None of these

Answer: C₆H₆

Question: But–2–yne on chlorination gives

• a) 2, 2, 3, 3 –tetrachlorobutane
• b) 1, 1, 2, 2 –tetrachlorobutane
• c) 1, 2 –dichlorobutane
• d) 1 –chlorobutane

Answer: 2, 2, 3, 3 –tetrachlorobutane

Question: When propyne reacts with aqueous H₂SO₄ in the presence of HgSO₄, the major product is

• a) Acetone
• b) Propanol
• c) Propyl hydrogen sulphate
• d) Propanal

Answer: Acetone

Question: Propyne on polymerisation gives

• a) Mesitylene
• b) Ethyl benzene
• c) Benzene
• d) Propyl benzene

Answer: Mesitylene

Question: What happens when a mixture of acetylene and hydrogen is passed over heated Lindlar’s catalyst ?

• a) Ethylene is formed
• b) Ethane and water are formed
• c) Acetylene and ethane are formed
• d) None of these

Answer: Ethylene is formed

Question:  Which of the following reaction is shown by alkynes

• a) All of these
• b) Substitution
• c) Addition
• d) Polymerization

Answer: All of these

Question: Which of the following reactions will yield 2, 2-dibromopropane ?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) Br₂, HBr, CH₃COCH₃, CH₃CHO
• b) HBr, Br₂, CH₃COCH₃, CH₃CHO
• c) HBr, HBr, CH₃COCH₃, CH₃CHO
• d) None of these

Answer: Br₂, HBr, CH₃COCH₃, CH₃CHO

Question: Which of the following polymer can be used as electrodes in batteries ?

• a) Polyacetylene
• b) Polyisoprene
• c) Polypropene
• d) Polyethene

Answer: Polyacetylene

Question:  Which of the following catalyst is used for the following conversion ?

• a) Red hot iron tube
• b) Iron-molybdenum
• c) Platinized Asbestos
• d) Platinized Nickel

Answer: Red hot iron tube

Question: Which one of the following is a non-benzenoid aromatic compound?

• a) Tropolone
• b) Benzoic acid
• c) Aniline
• d) Naphthalene

Answer: Tropolone

Question: Benzene was discovered by

• a) Faraday
• b) Ramsay
• c) Dalton
• d) Priestley

Answer: Faraday

Question: The ring structure of benzene was proposed by

• a) Kekule
• b) Faraday
• c) Davy
• d) Wohler

Answer: Kekule

Question: Six carbon atoms f benzene are of

• a) one type
• b) three types
• c) two types
• d) six types

Answer: one type

Question: Select the true statement about benzene amongst the following

• a) There is cyclic delocalisation of pi-electrons in benzene
• b) Monosubstitution of benzene gives three isomeric products
• c) There are two types of C – C bonds in benzene molecule
• d) Because of unsaturation benzene easily undergoes addition

Answer: There is cyclic delocalisation of pi-electrons in benzene

Question: The benzene molecule contains

• a) 6 sp² hybrid carbons
• b) 6 sp³ hybrid carbons
• c) 3 sp² hybrid carbons
• d) 3 sp³ hybrid carbons

Answer: 6 sp² hybrid carbons

Question: Aromatic compounds burn with sooty flame because

• a) they have a relatively high percentage of carbon
• b) they resist reaction with oxygen of air
• c) they have a relatively high percentage of hydrogen
• d) they have a ring structure of carbon atoms

Answer: they have a relatively high percentage of carbon

Question: Carbon atom in benzene molecule is inclined at an angle of

• a) 120°
• b) 180°
• c) 60°
• d) 109° 28'

Answer: 120°

Question:  The chemical system that is non-aromatic is

• a)

  

• b)

  

• c)

  

• d) Nne of these

Answer:

Question: Benzene can be directly obtained from

• a) All the above
• b) Phenol
• c) Acetylene
• d) Chlorobenzene

Answer: All the above

Question:

• a) Benzene
• b) Toluene
• c) Benzaldehyde
• d) Benzoic acid

Answer: Benzene

Question: In a reaction of C₆H₅Y, the major product (> 60%) is m-isomer, so the group Y is

• a) –COOH
• b) –OH
• c) –NH₂
• d) –Cl

Answer: –COOH

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Chlorobenzene is o, p-directing in electrophilic substitution reaction. The directing influence is explained by

• a) +M of Cl
• b) +M of Ph
• c) +I of Cl
• d) +I of Ph

Answer: +M of Cl

Question: Catalytic hydrogenation of benzene gives

• a) cyclohexane
• b) toluene
• c) xylene
• d) benzoic acid

Answer: cyclohexane

Question: The strongest ortho - para and strongest meta - directing groups respectively are

• a) –NH₂ and –NO₂
• b) –CONH₂ and –NH₂
• c) –NO₂ and –NH₂
• d) None of these

Answer: –NH₂ and –NO₂

Question: For the formation of toluene by Friedal Craft reaction, reactants used in presence of anhydrous AlCl₃ are

• a) CH₄ and CaCN₂
• b) C₂H₅ OH and Zn
• c) C₂H₂ and CCl₄
• d) None of these

Answer: CH₄ and CaCN₂

Question: Benzene can be obtained in the reaction

• a) Trimerisation of ethyne
• b) Reduction of PhCHO
• c) All of these
• d) Ethene + 1, 3-butadiene

Answer: Trimerisation of ethyne

Question: Nitration of benzene by nitric acid and sulphuric acid is

• a) Electrophilic substitution
• b) Electrophilic addition
• c) Nucleophilic substitution
• d) Free radical substitution

Answer: Electrophilic substitution

Question:

• a) Friedel - Craft’s reaction
• b) Kolbe’s synthesis
• c) Wurtz reaction
• d) Grignard reaction

Answer: Friedel - Craft’s reaction

Question: Benzene reacts with CH₃COCl + AlCl₃ to give

• a) acetophenone
• b) toluene
• c) chlorobenzene
• d) benzyl chloride

Answer: acetophenone

Question: Benzene on reaction with ozone forms __________.

• a) triozonide
• b) hexaozonide
• c) 2 molecules of ketone and 1 molecule of aldehyde
• d) 2 molecules of aldehyde and 1 molecule of ketone

Answer: triozonide

Question: AlCl₃ acts as ________ in Friedel-Crafts reaction

• a) electrophile
• b) intermediate
• c) nucleophile
• d) free radical

Answer: electrophile

Question: The electrophilic substitutions reactions of benzene takes place via

(i) generation of electrophile
(ii) generation of nucleophile
(iii) formation of carbocation intermediate
(iv) removal of proton from the carbocation intermediate

• a) (i), (iii) and (iv)
• b) (i) and (iv)
• c) (ii), (iii) and (iv)
• d) (ii) and (iv)

Answer: (i), (iii) and (iv)

Question: During the nitration of benzene. In the process of generation of nitronium ion sulphuric acid behaves as a/an ______ and nitric acid behave as a/an

• a) acid, base
• b) weak acid, strong acid
• c) base, acid
• d) strong acid, weak acid

Answer: acid, base

Question: Benzene is highly unsaturated but it does not undergo addition reaction because

• a)

  

• b) cyclic structures do not show addition reaction
• c) benzene is a non-reactive compound
• d) All of the above

Answer:

Question:  Which of the following statements are correct ?

(i) LNG is obtained by liquefaction of natural gas.
(ii) Petrol is obtained by fractional distillation of petroleum.
(iii) Coal gas is obtained by destructive distillation of coal.
(iv) CNG is found in upper strata during drilling of oil wells

• a) (ii) and (iv)
• b) (i), (ii) and (iii)
• c) (i), (ii) and (iv)
• d) (i) and (iii)

Answer: (ii) and (iv)

Question:  Which of the following statements are correct ?

(i) Saturated hydrocarbons contain only carbon-carbon single bonds.
(ii) Saturated hydrocarbons contain both carbon-carbon and carbon-hydrogen single bond.
(iii) Unsaturated hydrocarbons contain carbon-carbon double bonds.
(iv) Unsaturated hydrocarbons contain carbon-carbon double and triple bonds both.

• a) (ii) and (iv)
• b) (i) and (iv)
• c) (i) and (iii)
• d) (i) and (ii)

Answer: (ii) and (iv)

Question:  Which of the following statements are correct regarding structure of methane ?

(i) Methane has tetrahedral structure.
(ii) The bond angle between all H – C – H bonds is 109.5°.
(iii) The carbon atom is sp² hybridized.
(iv) C – C and C – H bond lengths are 154 pm and 112 pm respectively.

• a) (i), (ii) and (iv)
• b) (i), (ii) and (iii)
• c) (i), (iii) and (iv)
• d) (i), (ii), (iii) and (iv)

Answer: (i), (ii) and (iv)

Question: In the preparation of alkanes from hydrogenation of alkenes and alkynes. Finely divided catalysts are used which of the following statement(s) is/are correct regarding these catalysts

(i) Platinum and palladium catalyse the reaction at room temperature.
(ii) Nickel catalyse the reaction at relatively higher temperature and pressure.
(iii) Platinum and palladium catalyse the reaction at higher temperature

• a) (i) and (ii)
• b) (i) only
• c) (i) and (iii)
• d) (ii) and (iii)

Answer: (i) and (ii)

Question: Which of the following statements are correct ?

(i) The rate of reactivity of alkanes with halogens is F₂ > Cl₂ > Br₂ > I₂.
(ii) Rate of replacement of hydrogens of alkanes is 3° > 2º > 1°
(iii) Fluorination of alkanes is a very slow process.
(iv) Iodination of alkanes is too violent to be controlled

• a) (i) and (ii)
• b) (i) and (iv)
• c) (i), (ii) and (iii)
• d) (ii) and (iii)

Answer: (i) and (ii)

Question: Which of the following statements are correct ?

(i) Decomposition reaction of higher alkanes into smaller fragments by the application of heat is called pyrolysis.
(ii) Pyrolysis and cracking are different processes.
(iii) Dodecane on pyrolysis gives a mixture of heptane and pentene.
(iv) Pyrolysis follow free radical mechanism.

• a) (i), (iii) and (iv)
• b) (i), (ii) and (iv)
• c) (i), (iii) and (iv)
• d) None of these

Answer: (i), (iii) and (iv)

Question: Which of the following statement(s) is/are correct ?

(i) Alkanes can have infinite number of conformations by rotation around a C – C single bonds.
(ii) Rotation around C – C single bond is completely free.
(iii) Rotation is hindered by a small energy barrier of 1-20 kJ mol^–1 due to torsional strain

• a) (i) and (iii)
• b) Only (iii)
• c) (i) and (ii)
• d) (ii) and (iii)

Answer: (i) and (iii)

Question: Which of the following statements are correct ?

(i) Stability of conformation is affected due to torsional strain.
(ii) Magnitude of torsional strain depends upon the angle of rotation about C – C bond.
(iii) Eclipsed form has least torsional strain.
(iv) Staggered form has maximum torsional strain

• a) (i) and (ii)
• b) (i) and (iv)
• c) (i) and (iii)
• d) (iii) and (iv)

Answer: (i) and (ii)

Question: Which of the following statements are correct ?

(i) Cis form of alkene is polar whereas trans form is non-polar
(ii) Cis form of alkene is non-polar whereas trans form is polar.
(iii) In case of solid alkenes the trans isomer has higher melting point than the cis isomer.
(iv) Cis and trans both form have same properties

• a) (i) and (iii)
• b) (i), (iii) and (iv)
• c) (ii) and (iii)
• d) (i) and (iv)

Answer: (i) and (iii)

Question: Which of the following statements are correct ?

(i) Alkynes on reduction with palladised charcoal form cis alkenes.
(ii) Alkynes on reduction with palladised charcoal form trans alkenes.
(iii) Alkynes on reduction with sodium in liquid ammonia form trans alkenes.
(iv) Propyne on reduction with palladised charcoal form a mixture of cis and trans propene.

• a) (i) and (iii)
• b) (i), (iii) and (iv)
• c) (i) and (iv)
• d) (ii) and (iv)

Answer: (i) and (iii)

Question: Which of the following statements are correct ?

(i) Polynuclear hydrocarbons contain two or more benzene rings fused together.
(ii) Polynuclear hydrocarbons have carcinogenic property.
(iii) Polynuclear hydrocarbons are formed on incomplete combustion of organic materials like tobacco, coal and petroleum.
(iv) They are also produced in human body due to various biochemical reactions.

• a) (i), (ii) and (iii)
• b) (i), (iii) and (iv)
• c) (i), (ii) and (iv)
• d) (ii), (iii) and (iv)

Answer: (i), (ii) and (iii)

Question:

• a) A – (r), B – (p), C – (q)
• b) A – (p), B – (q), C – (r)
• c) A – (r), B – (q), C – (p)
• d) A – (q), B – ( p), C – (r)

Answer: A – (r), B – (p), C – (q)

Question: Bond angle in alkenes is equal to

• a) 120°
• b) 180°
• c) Both
• d) None of these

Answer: 120°