JEE Chemistry Hydrocarbons MCQs Set B

Question. Number of alkynes for formula C₅H₈ is –
(a) 3
(b) 5
(c) 2
(d) 4

Answer: A

Question. The homologue of ethyne is
(a) C₃H₆
(b) C₂H₆
(c) C₂H₄
(d) None of these

Answer: A

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: A

Question. Maximum carbon-carbon bond distance is found in –
(a) ethane
(b) ethyne
(c) ethene
(d) benzene

Answer: A

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: A

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: A

Question. Calcium carbide when treated with water gives
(a) acetylene
(b) ethylene
(c) methane
(d) ethane

Answer: A

Question. Which one of the following has the minimum boiling point ?
(a) Isobutane
(b) 1-Butyne
(c) 1-Butene
(d) n- Butane

Answer: A

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: A

Question.  Which of these will not react with acetylene?
(a) NaOH
(b) Na
(c) Ammonical AgNO₃
(d) HCl.

Answer: A

Question. When acetylene is passed over heated iron tube, the product obtained is –
(a) C₆H₆
(b) C₂H₂
(c) C₄H₄
(d) None of these

Answer: A

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: A

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: A

Question. Propyne on polymerisation gives
(a) Mesitylene
(b) Ethyl benzene
(c) Benzene
(d) Propyl benzene

Answer: A

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: A

Question.  Which of the following reaction is shown by alkynes
(a) All of these
(b) Substitution
(c) Addition
(d) Polymerization

Answer: A

Question. Which of the following polymer can be used as electrodes in batteries ?
(a) Polyacetylene
(b) Polyisoprene
(c) Polypropene
(d) Polyethene

Answer: A

Question. Which one of the following is a non-benzenoid aromatic compound?
(a) Tropolone
(b) Benzoic acid
(c) Aniline
(d) Naphthalene

Answer: A

Question. Benzene was discovered by
(a) Faraday
(b) Ramsay
(c) Dalton
(d) Priestley

Answer: A

Question. The ring structure of benzene was proposed by
(a) Kekule
(b) Faraday
(c) Davy
(d) Wohler

Answer: A

Question. Six carbon atoms f benzene are of
(a) one type
(b) three types
(c) two types
(d) six types

Answer: A

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: A

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: A

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: A

Question. Carbon atom in benzene molecule is inclined at an angle of
(a) 120°
(b) 180°
(c) 60°
(d) 109° 28'

Answer: A

Question. Benzene can be directly obtained from
(a) All the above
(b) Phenol
(c) Acetylene
(d) Chlorobenzene

Answer: A

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: A

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: A

Question. Catalytic hydrogenation of benzene gives
(a) cyclohexane
(b) toluene
(c) xylene
(d) benzoic acid

Answer: A

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: A

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: A

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: A

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: A

Question. Benzene reacts with CH₃COCl + AlCl₃ to give
(a) acetophenone
(b) toluene
(c) chlorobenzene
(d) benzyl chloride

Answer: A

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: A

Question. AlCl₃ acts as ________ in Friedel-Crafts reaction
(a) electrophile
(b) intermediate
(c) nucleophile
(d) free radical

Answer: A

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: A

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: A

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: A

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: A

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: A

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: A

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: A

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) and (ii)
(d) None of these

Answer: A

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: A

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: A

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: A

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: A

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: A

Question. Bond angle in alkenes is equal to
(a) 120°
(b) 180°
(c) Both
(d) None of these

Answer: A