JEE Main - Alkenes electrophilic addition Markovnikov and peroxide effects and polymerization Online Test (MCQ Quiz)

1. Which type of reaction is the addition of HBr to an alkene in the absence of peroxides?

A) Free radical addition B) Electrophilic addition C) Nucleophilic addition D) Elimination reaction

2. According to Markovnikov's rule, in the addition of an unsymmetrical reagent like HBr to an unsymmetrical alkene, the hydrogen atom of the reagent attaches to the carbon atom that has:

A) Fewer hydrogen atoms B) More hydrogen atoms C) An equal number of hydrogen atoms D) The least number of carbon atoms

3. The addition of HBr to propene in the presence of organic peroxides follows which mechanism?

A) Electrophilic addition B) Nucleophilic addition C) Free radical addition D) Rearrangement reaction

4. When HBr is added to propene in the presence of peroxides, the major product formed is:

A) 1-bromopropane B) 2-bromopropane C) Propane D) Propyne

5. The peroxide effect is observed with which hydrogen halide addition to alkenes?

A) HCl B) HBr C) HI D) HF

6. The peroxide effect in the addition of HBr to alkenes is an example of which type of addition?

A) Ionic addition B) Radical addition C) Concerted addition D) Acid-catalyzed addition

7. Which of the following is a common initiator for free radical addition reactions of alkenes?

A) Strong acids B) Metal catalysts C) Organic peroxides D) Water

8. Polymerization of ethene to polythene is an example of which type of polymerization?

A) Addition polymerization B) Condensation polymerization C) Copolymerization D) Ziegler-Natta polymerization

9. In the addition polymerization of alkenes, the monomer units are joined together by:

A) Elimination of small molecules B) Formation of new sigma bonds C) Formation of new pi bonds D) Transfer of electrons

10. Which catalyst is typically used in the Ziegler-Natta polymerization of alkenes?

A) Peroxides B) Lewis acids C) Organometallic compounds D) Strong bases

11. The mechanism of addition polymerization of alkenes usually involves:

A) Carbocation intermediates B) Carbanion intermediates C) Free radical intermediates D) All of the above

12. Which of the following alkenes can undergo addition polymerization?

A) Ethane B) Ethene C) Ethyne D) Methane

13. The anti-Markovnikov addition of HBr to an alkene is favored by:

A) High concentration of HBr B) Presence of peroxides C) Absence of light D) Low temperature

14. The intermediate formed in the electrophilic addition of HBr to propene is a:

A) Carbon radical B) Carbonium ion (carbocation) C) Carbanion D) Transition state complex

15. The carbocation formed during the electrophilic addition of HBr to propene is:

A) Primary carbocation B) Secondary carbocation C) Tertiary carbocation D) Allylic carbocation

16. The stability order of carbocations is:

A) Primary > Secondary > Tertiary B) Tertiary > Secondary > Primary C) Secondary > Primary > Tertiary D) Tertiary > Primary > Secondary

17. Which of the following is a characteristic of addition polymerization?

A) Formation of by-products B) Monomers combine without loss of atoms C) Involves functional groups D) Requires high temperature and pressure only

18. Polymerization of vinyl chloride (chloroethene) yields:

A) Polypropylene B) Polystyrene C) Polyvinyl chloride (PVC) D) Teflon

19. The addition of water to an alkene in the presence of an acid catalyst is an example of:

A) Free radical addition B) Electrophilic addition C) Nucleophilic addition D) Oxidation reaction

20. The intermediate in the free radical addition of HBr to an alkene involves the formation of:

A) A carbocation B) A carbanion C) A carbon radical D) A resonance-stabilized anion

21. Which bond is broken in the pi bond of an alkene during electrophilic addition?

A) Sigma bond B) Pi bond C) Both sigma and pi bonds D) Neither bond

22. The peroxide effect is a result of:

A) Increased electrophilicity of HBr B) Generation of free radicals C) Formation of a more stable carbocation D) Acid catalysis

23. Which of the following alkenes will give a mixture of products in the electrophilic addition of HBr due to the formation of a more stable carbocation?

A) Ethene B) Propene C) But-1-ene D) But-2-ene

24. In the free radical addition of HBr, the chain propagation step involves:

A) Attack of Br- on the alkene B) Attack of H+ on the alkene C) Attack of Br• on the alkene D) Attack of H• on the alkene

25. Polymerization of styrene (vinylbenzene) results in:

A) Polyethylene B) Polypropylene C) Polystyrene D) Polyvinyl chloride

26. The addition of a symmetrical reagent like Br2 to an alkene follows which rule?

A) Markovnikov's rule B) Anti-Markovnikov's rule C) Hund's rule D) Aufbau principle

27. The addition of Br2 to ethene forms:

A) 1,1-dibromoethane B) 1,2-dibromoethane C) Bromoethane D) Ethyne

28. The reaction of an alkene with halogens in the presence of water leads to the formation of:

A) Dihalides B) Halohydrins C) Alcohols D) Alkanes

29. Which of the following is NOT an example of addition polymerization?

A) Polymerization of ethene B) Polymerization of propene C) Polymerization of vinyl chloride D) Formation of nylon-6,6

30. The product formed by the addition of HBr to 2-methylbut-2-ene according to Markovnikov's rule is:

A) 2-bromo-2-methylbutane B) 1-bromo-2-methylbutane C) 2-bromo-3-methylbutane D) 3-bromo-2-methylbutane

31. In the free radical polymerization of alkenes, the chain termination step can occur by:

A) Combination of two growing radicals B) Disproportionation of two growing radicals C) Both a and b D) Chain transfer

32. The addition of H2O to but-1-ene in acidic medium yields:

A) Butan-1-ol B) Butan-2-ol C) Butane D) 1-chlorobutane

33. The peroxide effect is an exception to which rule?

A) Markovnikov's rule B) Kekulé's rule C) Saytzeff's rule D) Hofmann's rule

34. Which of the following initiators is suitable for free radical polymerization?

A) Benzoyl peroxide B) Concentrated sulfuric acid C) Aluminum chloride D) Sodium hydroxide

35. The polymerization of tetrafluoroethene (CF2=CF2) yields:

A) Polyethylene B) Polypropylene C) Polytetrafluoroethene (Teflon) D) Polyvinyl chloride

36. In the electrophilic addition of HBr to an unsymmetrical alkene, the rate-determining step is:

A) The attack of the electrophile (H+) on the alkene B) The attack of the nucleophile (Br-) on the carbocation C) The formation of the pi-complex D) Protonation of the alkene

37. The product formed by the anti-Markovnikov addition of HBr to 2-methylbut-1-ene is:

A) 1-bromo-2-methylbutane B) 2-bromo-2-methylbutane C) 2-bromo-1-methylbutane D) 3-bromo-2-methylbutane

38. Which type of polymerization is commonly used for monomers with double bonds?

A) Condensation polymerization B) Addition polymerization C) Ring-opening polymerization D) Block polymerization

39. The addition of HI to an unsymmetrical alkene in the presence of peroxides follows:

A) Markovnikov's rule B) Anti-Markovnikov's rule C) Neither rule D) Both rules equally

40. The formation of a carbocation in electrophilic addition leads to:

A) Retention of configuration B) Inversion of configuration C) Racemization D) Anti-addition

41. Which of the following is a characteristic of anti-Markovnikov addition?

A) Hydrogen adds to the carbon with fewer hydrogens. B) Halogen adds to the carbon with fewer hydrogens. C) Hydrogen adds to the carbon with more hydrogens. D) Halogen adds to the carbon with more hydrogens.

42. What is the role of peroxides in the addition of HBr to alkenes?

A) They act as catalysts to increase the rate of electrophilic addition. B) They initiate a free radical chain mechanism. C) They stabilize the carbocation intermediate. D) They prevent the addition of HBr.

43. The chain transfer step in free radical polymerization involves:

A) Termination of the growing chain. B) Initiation of a new chain by a radical. C) Transfer of a radical from a growing chain to another molecule. D) Combination of two growing chains.

44. Which of the following is a property of polythene?

A) High tensile strength B) Chemical inertness C) Brittleness D) High melting point

45. The addition of Br2 to propene in the absence of peroxides yields:

A) 1,2-dibromopropane B) 1,1-dibromopropane C) 2,2-dibromopropane D) 2-bromopropane

46. In free radical addition of HBr to an unsymmetrical alkene, the regioselectivity is determined by:

A) Stability of the carbocation formed B) Stability of the intermediate radical C) Electronegativity of the atoms D) Steric hindrance

47. The product formed by the addition of HBr to 1-phenylpropene according to Markovnikov's rule is:

A) 1-bromo-1-phenylpropane B) 1-bromo-2-phenylpropane C) 2-bromo-1-phenylpropane D) 2-bromo-2-phenylpropane

48. Which type of bonding is formed between monomer units during addition polymerization?

A) Ionic bonds B) Hydrogen bonds C) Covalent bonds D) Metallic bonds

49. The addition of H2O to but-2-ene in acidic medium yields:

A) Butan-1-ol B) Butan-2-ol C) Butane D) 2-chlorobutane

50. Which of the following is a consequence of the peroxide effect?

A) Reversal of regioselectivity compared to Markovnikov's rule. B) Increased rate of electrophilic addition. C) Formation of ionic intermediates. D) Addition of H2O instead of HBr.

Alkenes electrophilic addition Markovnikov and peroxide effects and polymerization - Online Test

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