Quiz  /  Alkene Class 12 MCQ Questions With Answers

  • 1. 
    What is the product of the Br2 addition to methycyclohexene?

  • 1,2-dibromo-1-methylcyclohexene
  • 1,2-dibromo-1-methylcyclohexane

  • 2. 
    Which correctly represents an incomplete combustion of pentane?

  • C5H12 + 8O2 ⟶ 5CO2 + 6H2O
  • C5H12 + 8O2 ⟶ 4CO + CO2 + 6H2O
  • C5H12 + 6O2 ⟶ 4CO + CO2 + 6H2O
  • C5H12 + 5O2 ⟶ 4CO + CO2 + 4H2O + 2H2

  • 3. 
    Which one of the following mechanisms is not involved in the reaction sequence below?CH3CH3 → CH3CH2Cl → CH3CH2OH → CH2=CH2 → CH3CH2Br

  • electrophilic addition
  • electrophilic substitution
  • nucleophilic substitution
  • free-radical substitution

  • 4. 
    What is the major product of the reaction between but-1-ene and DBr? (D is deuterium and represents 2H)

  • CH2DCH2CH2CH2Br
  • CH2DCH2CHBrCH3
  • CH3CH2CHBrCH2D
  • CH3CH2CHDCH2Br

  • 5. 
    Which of the following mechanisms does not occur in reactions of bromoethane?

  • Electrophilic addition
  • Elimination
  • Nucleophilic substitution
  • Radical substitution

  • 6. 
    In which of the following is a curly arrow used incorrectly?

  • A
  • B
  • C
  • D

  • 7. 
    Pentanenitrile can be made by reaction of 1-bromobutane with potassium cyanide.Which of these is the correct name for the mechanism of this reaction?

  • Electrophilic addition
  • Electrophilic substitution
  • Nucleophilic addition
  • Nucleophilic substitution

  • 8. 
    The correct name for the alkene monomer which forms the polymer shown above is

  • 2-methyl-3-ethylpropene
  • 2-methylpent-2-ene
  • 2-methylpent-3-ene
  • 4-methylpent-2-ene

  • 9. 
    This question is about a method that can be used to prepare ethylamine.CH3CH2Br + 2NH3 = CH3CH2NH2 + NH4BrWhich statement about the reaction is not correct?

  • Ethylamine is a primary amine.
  • The mechanism is a nucleophilic substitution.
  • Using an excess of bromoethane will prevent further reaction to form a mixture of amine products.
  • Ammonium bromide is an ionic compound.

  • 10. 
    Which one of the following statements explains best why fluoroalkanes are the least reactive haloalkanes?

  • Fluorine is much more electronegative than carbon.
  • The F− ion is the most stable halide ion.
  • The C–F bond is the most polar carbon–halogen bond.
  • The C–F bond is the strongest carbon–halogen bond.

  • 11. 
    Which statement about E-1,2-dichloroethene is NOT correct?

  • It has the same boiling point as Z-1,2-dichloroethene.
  • It forms a polymer with the same repeating unitas Z-1,2-dichloroethene.
  • It has the same IR spectrum as Z-1,2-dichloroethenein the range 400–1500 cm−1.
  • It has a molecular ion peak different from that ofZ-1,2-dichloroethene in its mass spectrum.

  • 12. 
    The structure of the molecule of methyl 2-methylpropenoate is shown below. Which one of the following statements concerning this compound is not true?

  • It displays geometrical isomerism.
  • It forms an addition polymer.
  • It undergoes reduction.
  • It decolourises bromine.

  • 13. 
    What is the empirical formula of 4-hydroxypent-2-ene?

  • C5H12O
  • C5H10O
  • CH2O
  • C5H9OH

  • 14. 
    Which statement about ethene is correct?

  • It has no geometric isomers because there is free rotation around the C=C bond.
  • It reacts with HBr in a nucleophilic addition reaction.
  • It burns in excess oxygen to produce carbon dioxide and water.
  • The C=C bond is twice as strong as the C–C bond in ethane.

  • 15. 
    The correct systematic name for the molecule shown is ...

  • 2-ethyl-3,4-dimethylpent-2-ene
  • 4-ethyl-2,3-dimethylpent-3-ene
  • 2,3,4-trirnethylhex-3-ene
  • 3,4,5-trimethylhex-3-ene

  • 16. 
    Which is the major product of the reaction between 2-methylbut-2-ene and iodine monochloride (ICl)?

  • A
  • B
  • C
  • D

  • 17. 
    Tetradecane (C14H30) is an alkane found in crude oil. When tetradecane is heated to a high temperature, one molecule of tetradecane decomposes to form one molecule of hexane and three more molecules.Which of the following could represent this reaction?

  • C14H30 → C6H14 + C4H8 + 2C2H4
  • C14H30 → C6H14 + C6H12 + C2H4
  • C14H30 → C5H12 + 3C3H6
  • C14H30 → C6H14 + C2H6 + 2C3H6

  • 18. 
    How many different alkenes are formed when 2-bromo-2-methylbutane reacts with ethanolic potassium hydroxide?

  • 2
  • 3
  • 4
  • 5

  • 19. 
    Which molecule is not produced when ethane reacts with bromine in the presence of ultraviolet light?

  • C2H4Br2
  • HBr
  • H2
  • C4H10

  • 20. 
    What are the products formed when organic compounds burn completely ?

  • carbon and oxygen
  • carbon dioxide and water
  • carbon, carbon monoxide and water
  • carbon, carbon dioxide and water

  • 21. 
    The "ane" ending in "alkane" tells someone that they are dealing with _________-bonded carbons.

  • single
  • double
  • triple
  • quadruple

  • 22. 
    What liquid detects the presence of an alkene?

  • Alkene water
  • Bromine water
  • Water
  • Limewater

  • 23. 
    A compound consists of carbon and hydrogen elements only. It also contains a carbon-carbon double bond. This compound is known as

  • saturated organic compound
  • unsaturated organic compound
  • saturated hydrocarbon
  • unsaturated hydrocarbon

  • 24. 
    General formula of Alkene is

  • CnH2n+2
  • CnH2n
  • CnH2n+1OH
  • CnH2n+1COOH

  • 25. 
    Complete the equation C16H34 ---> __________ + C2H4

  • C16H34
  • C2H30
  • C10H20
  • C14H30

  • 26. 
    Which of the following is a saturated hydrocarbon?

  • ethene
  • heptane
  • propyne
  • methanol

  • 27. 
    Which of the following is unsaturated hydrocarbon ?

  • propane
  • propene
  • propanol
  • propanoic acid
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