Here’s a bank of 60 multiple-choice questions (MCQs) on the topic of hydrocarbons, categorized by difficulty level and tailored for BISE, Gujranwala. Answers are provided at the end.
Easy Questions
1. What are hydrocarbons?
- A) Compounds containing carbon and nitrogen
- B) Compounds containing only carbon and hydrogen
- C) Compounds containing carbon and oxygen
- D) Compounds containing only hydrogen
2. Which of the following is an example of an alkane?
- A) Ethylene
- B) Acetylene
- C) Propane
- D) Butadiene
3. What type of hydrocarbon has a straight or branched chain structure?
- A) Cyclic hydrocarbons
- B) Aromatic hydrocarbons
- C) Open-chain hydrocarbons
- D) Alicyclic hydrocarbons
4. What is the general formula for alkanes?
- A) CnH2n+2
- B) CnH2n
- C) CnH2n-2
- D) CnH2n+1
5. From which natural resource are alkanes primarily obtained?
- A) Coal
- B) Natural gas
- C) Minerals
- D) Plants
6. Which process is used to prepare alkanes from alkyl halides?
- A) Hydrolysis
- B) Reduction
- C) Oxidation
- D) Halogenation
7. What is the main physical property of alkanes?
- A) High reactivity
- B) Low boiling points
- C) Low density
- D) Strong odor
8. What type of reaction occurs when alkanes react with halogens?
- A) Combustion
- B) Halogenation
- C) Hydrogenation
- D) Dehydration
9. Which of the following is a product of alkane combustion?
- A) Oxygen
- B) Water
- C) Carbon dioxide
- D) Both B and C
10. What is methane commonly used for?
- A) Fuel
- B) Solvent
- C) Plastic production
- D) All of the above
11. What type of hydrocarbon contains at least one double bond?
- A) Alkane
- B) Alkene
- C) Alkyne
- D) Cycloalkane
12. Which of the following is a property of alkenes?
- A) Saturated
- B) Unsaturated
- C) Low reactivity
- D) High boiling point
13. What is the dehydration of alcohols?
- A) Addition of water
- B) Removal of water
- C) Addition of hydrogen
- D) Addition of halogens
14. What is the outcome of dehydrohalogenation of alkyl halides?
- A) Formation of alcohols
- B) Formation of alkenes
- C) Formation of alkanes
- D) Formation of ethers
15. What type of reaction involves the addition of hydrogen to alkenes?
- A) Dehydration
- B) Halogenation
- C) Hydrogenation
- D) Hydrolysis
16. What happens when alkenes are oxidized with KMnO4?
- A) They form alcohols
- B) They form ketones
- C) They remain unchanged
- D) They form alkanes
17. Which of the following alkenes is used in the production of polyethylene?
- A) Propene
- B) Ethene
- C) Butene
- D) Hexene
18. Which of the following compounds is an alkyne?
- A) Ethylene
- B) Propene
- C) Acetylene
- D) Cyclohexane
Moderate Question
19. What is the primary use of ethane in industries?
- A) Solvent
- B) Fuel
- C) Refrigerant
- D) Plastic production
20. What is a characteristic reaction of alkenes?
- A) Substitution
- B) Addition
- C) Elimination
- D) Hydrolysis
21. Which reaction converts alkynes into alkenes?
- A) Hydrogenation
- B) Dehydrohalogenation
- C) Hydrohalogenation
- D) Oxidation
22. What type of isomerism can alkenes exhibit?
- A) Structural isomerism
- B) Geometric isomerism
- C) Optical isomerism
- D) All of the above
23. Which of the following is a property of alkynes?
- A) Low boiling point
- B) High reactivity
- C) Low density
- D) High melting point
24. What is the result of the halogenation of alkenes?
- A) Formation of alkynes
- B) Formation of dihalides
- C) Formation of alcohols
- D) Formation of alkanes
25. Which reaction involves the elimination of HX from alkyl halides?
- A) Dehydrohalogenation
- B) Halogenation
- C) Hydrogenation
- D) Oxidation
26. What does the oxidation of alkenes with KMnO4 typically produce?
- A) Alcohols
- B) Aldehydes
- C) Carboxylic acids
- D) Alkanes
27. How can alkynes be prepared from vicinal dihalides?
- A) Halogenation
- B) Dehalogenation
- C) Reduction
- D) Oxidation
28. What type of reaction is the addition of halogen to an alkene?
- A) Substitution
- B) Addition
- C) Elimination
- D) Hydrolysis
29. What is acetylene commonly used for?
- A) Fuel for welding
- B) Plastic production
- C) Solvent
- D) Refrigerant
30. How do physical properties of hydrocarbons change with increasing carbon chain length?
- A) Decrease in boiling point
- B) Increase in density
- C) Increase in volatility
- D) No change
31. What is a common industrial use of acetylene?
- A) Synthesis of ethylene
- B) Synthesis of benzene
- C) Welding
- D) Fuel
32. What type of hydrocarbons can act as feedstock in the chemical industry?
- A) Only saturated hydrocarbons
- B) Only unsaturated hydrocarbons
- C) Both saturated and unsaturated hydrocarbons
- D) None
33. How does the presence of a double bond in alkenes affect their reactivity?
- A) Makes them less reactive
- B) Makes them more reactive
- C) No effect on reactivity
- D) Reactivity depends on other factors
34. Which compound is produced when ethylene reacts with hydrogen?
- A) Ethane
- B) Acetylene
- C) Ethanol
- D) Butane
35. Which of the following is an example of a vicinal dihalide?
- A) 1,2-Dichloroethane
- B) 1,1-Dichloroethane
- C) Ethylene
- D) Acetylene
36. What type of hydrocarbons typically undergo combustion?
- A) Only saturated hydrocarbons
- B) Only unsaturated hydrocarbons
- C) Both saturated and unsaturated hydrocarbons
- D) None
37. What is a key characteristic of hydrocarbons as feedstock?
- A) They are only gases
- B) They can be converted into various chemicals
- C) They have no economic value
- D) They are only found in oil
38. What process can convert an alkane into an alkene?
- A) Hydrogenation
- B) Cracking
- C) Hydration
- D) Polymerization
39. Which of the following hydrocarbons is considered a renewable resource?
- A) Coal
- B) Natural gas
- C) Bioethanol
- D) Propane
40. What is the main environmental concern associated with the combustion of hydrocarbons?
- A) Ozone depletion
- B) Global warming
- C) Soil degradation
- D) Water pollution
Tough Questions
41. How does the boiling point of branched alkanes compare to straight-chain alkanes?
- A) Higher boiling point
- B) Lower boiling point
- C) Same boiling point
- D) It varies with molecular weight
42. What is the role of catalysts in the hydrogenation of alkenes?
- A) To increase the temperature
- B) To lower the activation energy
- C) To decrease the pressure
- D) To provide hydrogen
43. What is the mechanism of the oxidation of alkenes using KMnO4?
- A) Electrophilic addition
- B) Free radical mechanism
- C) Nucleophilic substitution
- D) Electrophilic substitution
44. How does the reactivity of alkynes compare to that of alkenes?
- A) Alkynes are less reactive
- B) Alkynes are more reactive
- C) They are equally reactive
- D) Depends on the substituents
45. Which of the following reactions is an example of elimination?
- A) Halogenation of alkenes
- B) Dehydrohalogenation of alkyl halides
- C) Hydrogenation of alkenes
- D) Hydrolysis of alkynes
46. What is the outcome of adding a strong oxidizing agent to acetylene?
- A) Formation of alkynes
- B) Formation of carboxylic acids
- C) No reaction
- D) Formation of alcohols
47. Which product is formed when 1-butene undergoes hydrohalogenation?
- A) 2-Bromobutane
- B) 1-Bromobutane
- C) Butanol
- D) No reaction
48. What is the main product of the combustion of hydrocarbons?
- A) Hydrogen
- B) Carbon monoxide
- C) Water and carbon dioxide
- D) Methane
49. What type of reaction occurs when vicinal dihalides are dehydrohalogenated?
- A) Elimination
- B) Addition
- C) Substitution
- D) Hydrolysis
50. What is the significance of hydrocarbons in the chemical industry?
- A) They are used as fertilizers
- B) They serve as feedstock for chemical synthesis
- C) They are only used as fuels
- D) They have no industrial applications
51.What occurs during the halogenation of alkenes?
- A) Formation of alkanes
- B) Addition of halogens across the double bond
- C) Elimination of hydrogen
- D) No change in structure
52. What is the primary environmental impact of using hydrocarbons as fuel?
- A) Resource depletion
- B) Air pollution
- C) Soil contamination
- D) Water scarcity
53. Which type of hydrocarbon can participate in electrophilic addition reactions?
- A) Alkanes
- B) Alkenes
- C) Alkynes
- D) All of the above
54. What distinguishes alkenes from alkynes in terms of bonding?
- A) Alkenes have single bonds; alkynes have double bonds
- B) Alkenes have double bonds; alkynes have triple bonds
- C) Both have double bonds
- D) Both have single bonds
55. What reaction do alkenes undergo when treated with concentrated sulfuric acid?
- A) Substitution
- B) Hydration
- C) Dehydration
- D) Addition
56.Which of the following compounds can be classified as an aromatic hydrocarbon?
- A) Benzene
- B) Propane
- C) Ethylene
- D) Acetylene
57. How do physical properties such as density change with the increase of molecular size in hydrocarbons?
- A) Density decreases
- B) Density remains constant
- C) Density increases
- D) Density varies randomly
58. What is the primary product of complete combustion of hydrocarbons?
- A) Carbon monoxide
- B) Carbon dioxide
- C) Water
- D) Both B and C
59. What is the role of alkenes in the production of plastics?
- A) They serve as catalysts
- B) They are raw materials for polymerization
- C) They have no role in plastics
- D) They are byproducts
60. Which type of reaction results in the formation of a polymer from monomers?
- A) Decomposition
- B) Addition
- C) Elimination
- D) Substitution
Answers
1. B
2. C
3. C
4. A
5. B
6. B
7. C
8. B
9. D
10. A
11. B
12. B
13. B
14. B
15. C
16. A
17. B
18. C
19. A
20. B
21. A
22. D
23. B
24. B
25. A
26. A
27. B
28. B
29. A
30. B
31. C
32. C
33. B
34. A
35. A
36. C
37. B
38. B
39. C
40. B
41. B
42. B
43. A
44. B
45. B
46. B
47. A
48. C
49. A
50. B
51. B
52. B
53. B
54. B
55. B
56. A
57. C
58. D
59. B
60. B