Free Chemistry of Hydrocarbons MCQs with Answers
1,091 Chemistry of Hydrocarbons MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Hydrocarbons are studied through the structures and reactions of alkanes, alkenes, alkynes and aromatic compounds. Coverage includes free radical substitution in alkanes, electrophilic addition to carbon-carbon multiple bonds, benzene substitution, aromatic stability and the difference between addition reactions of alkenes and substitution reactions of benzene.
Last updated
Read the Chemistry of Hydrocarbons notesFree MDCAT chapter notes with key terms1,091 questions · page 18 of 55
- A. n-butyl chloride
- B. isobutyl chloride
- C. sec-butyl chloride
- D. tert-butyl chloride
Explanation: Free-radical chlorination of alkanes favors the formation of the most stable radical intermediate.
Correct answer: tert-butyl chloride342. The addition of HCl in the presence of peroxide does not follow anti-Markovnikov rule because :
- A. HCl bond is too strong to be broken homolytically by the peroxide
- B. Cl atom is not reactive enough to add on to a double bond.
- C. Cl combines with H to give back HCl.
- D. HCl is a reducing agent.
Explanation: The anti-Markovnikov mechanism is a free-radical process initiated by the peroxide.
Correct answer: HCl bond is too strong to be broken homolytically by the peroxide- A. Intensity of UV light
- B. Concentration of X2 used
- C. Temperature
- D. Both A and B
Explanation: Halogenation of alkanes is a radical substitution reaction initiated by UV light.
Correct answer: Both A and B- A. Reaction of free radical with another free radical
- B. Formation of two free radicals
- C. Consumption of a free radical and production of another free radical
- D. Reaction between two molecules
Explanation: A propagation step is a stage in a chain reaction where the number of free radicals is conserved.
Correct answer: Consumption of a free radical and production of another free radical- A. CH3Cl + HCl
- B. CHCl3 + 3HCl
- C. CCl4 + 4HCl
- D. CH2Cl2 + 2HCl
Explanation: The free-radical chlorination of methane is a chain reaction. When chlorine is used in large excess, the reaction will continue until the…
Correct answer: CH2Cl2 + 2HCl- A. Substitution, Alkane
- B. Dehydrohalogenation, Alkene
- C. Halogenation, Alkyne
- D. Dehydration, Alcohol
Explanation: This process is called dehydrohalogenation (a type of B-elimination). It involves the removal of a hydrogen and a halogen from adjacent…
Correct answer: Dehydrohalogenation, Alkene- A. P4O10
- B. conc. HNO3
- C. conc. H2SO4
- D. conc. H3PO4
Explanation: Concentrated sulfuric acid, phosphoric acid, and phosphorus pentoxide are all effective dehydrating agents used to convert alcohols to…
Correct answer: conc. HNO3- A. Bromine water test
- B. Baeyer's test (cold, dilute, alkaline KMNO4)
- C. Ozonolysis
- D. Both A and B
Explanation: The correct answer is Baeyer's test, as it specifically targets the unique reactivity of alkenes through oxidation, which alkanes do not…
Correct answer: Baeyer's test (cold, dilute, alkaline KMNO4)- A. Ethylene glycol
- B. Vicinal glycol
- C. Glyoxal
- D. Oxalic acid
Explanation: This reaction, known as the Baeyer test, involves the syn-dihydroxylation of the alkene's double bond.
Correct answer: Vicinal glycol- A. 1,3-Butadiene
- B. 1-Butyne
- C. 1-Butene
- D. 1,2-Butadiene
Explanation: The suffix "-ene" indicates a double bond, and the prefix "mono-" means one. A mono-ene is a hydrocarbon with only one double bond.
Correct answer: 1-Butene- A. Ethyne
- B. Propyne
- C. 1-butyne
- D. 2-butyne
Explanation: The hydration of alkynes typically follows Markovnikov's rule, producing a ketone.
Correct answer: Ethyne- A. Ethyne
- B. Propyne
- C. 1-butyne
- D. 2-butyne
Explanation: Terminal alkynes (ethyne, propyne, 1-butyne) have an acidic hydrogen on the sp-hybridized carbon.
Correct answer: 2-butyne- A. Alkane
- B. Alkene
- C. Benzene
- D. Alkyne
Explanation: Electrophilic addition occurs at π-bonds, which are electron-rich and easily attacked by electrophiles.
Correct answer: Alkene- A. Ethyne
- B. Propyne
- C. Ethane
- D. Propane
Explanation: The hydration of an alkyne with water in the presence of an acid and a mercury (II) catalyst adds an -OH group to one carbon and an -H to…
Correct answer: Propyne- A. White
- B. Red
- C. Orange
- D. Yellow
Explanation: Acetylene, as a terminal alkyne, reacts with Tollens' reagent (ammoniacal silver nitrate) in an acid-base reaction.
Correct answer: White- A. CH3-CH3
- B. CH3-CH=CH2
- C. CH≡CH
- D. CH3-C≡C-CH3
Explanation: The hydrogen atoms in terminal alkynes, like ethyne (acetylene), are sufficiently acidic to react with strong bases or active metals like…
Correct answer: CH≡CH- A. 3
- B. 6
- C. 12
- D. 18
Explanation: Each of the six carbon atoms in a benzene ring is sp² hybridized. Each sp² hybridized atom has three sp² hybrid orbitals.
Correct answer: 18- A. 3
- B. 4
- C. 8
- D. 6
Explanation: Each of the six sp²-hybridized carbon atoms in the benzene ring contributes one electron from its unhybridized p-orbital to the pi system.
Correct answer: 6359. What is required other than anhydrous ALCL3, when toluene is prepared by friedal craft reaction?
- A. C6H6 + CH3Cl
- B. C6H6 + CH4
- C. C6H5C2H5
- D. C6H5Cl + CH3Cl
Explanation: The Friedel-Crafts alkylation reaction to prepare toluene involves reacting benzene (C6H6) with an alkylating agent, such as methyl…
Correct answer: C6H6 + CH3Cl- A. Toluene
- B. o-Xylene
- C. m-Xylene
- D. Benzoic acid
Explanation: The first step is a Friedel-Crafts alkylation, which produces toluene. The second step is the strong oxidation of the alkyl side chain of…
Correct answer: Benzoic acid