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 2 of 55
- A. Terminal carbon atoms are sp hybridized
- B. Terminal carbon atoms are sp2 hybridized
- C. Terminal carbon atoms are sp3 hybridized
- D. Terminal carbon atoms show hydrogen bonding
Explanation: An sp hybrid orbital has 50 per cent s character, so it holds the bonding electrons closer to the carbon nucleus and the attached hydrogen…
Correct answer: Terminal carbon atoms are sp hybridized- A. Low pressure
- B. Low temperature
- C. High pressure
- D. Heat and UV light
Explanation: Initiation requires the halogen molecule to split homolytically into two radicals, and only ultraviolet light or a high temperature…
Correct answer: Heat and UV light- A. Aromaticity
- B. Stability
- C. To follow Huckel rule
- D. High reactivity
Explanation: The delocalised ring of six pi electrons makes benzene unusually stable, so it resists addition and reacts only under forcing conditions…
Correct answer: High reactivity- A. Electrophilic addition
- B. Electrophilic substitution
- C. Free radical substitution
- D. Free radical halogenation
Explanation: Iron three chloride acts as a halogen carrier, polarising the chlorine molecule to generate an electrophile that attacks the electron rich…
Correct answer: Electrophilic substitution- A. Ethane
- B. Methane
- C. Propane
- D. Butane
Explanation: Methane, CH4, is called marsh gas because it is produced by the anaerobic decomposition of organic matter in marshes and swamps.
Correct answer: Methane- A. Alkanes
- B. Alkynes
- C. Alkenes
- D. a & c
Explanation: Aliphatic hydrocarbons containing only carbon-carbon single covalent bonds are saturated hydrocarbons called alkanes, with the open-chain…
Correct answer: Alkanes- A. C4H6
- B. C5H12
- C. C3H4
- D. C6H10
Explanation: C5H12 fits the alkane formula CnH2n+2 because 2(5) + 2 = 12, so it is saturated rather than unsaturated.
Correct answer: C5H12- A. iso-octane
- B. n-hexane
- C. n-heptane
- D. iso-heptane
Explanation: The octane scale assigns 0 to n-heptane and 100 to iso-octane because these compounds represent the reference extremes for knocking…
Correct answer: n-heptane- A. (C2H5 )4Pb
- B. TNT
- C. CH MgBr3
- D. C2H5 )2Hg
Explanation: Tetraethyl lead, (C2H5)4Pb, was added to petrol as an antiknock agent because it reduced premature ignition and engine knocking.
Correct answer: (C2H5 )4Pb- A. 20% n- heptane + 80% iso-octane
- B. 80% n- heptane + 20% iso-octane
- C. 20% n- heptane + 80% n-octane
- D. 80% n-heptane + 20% n- octane
Explanation: An octane number of 80 means the petrol has the same knocking tendency as a mixture containing 80% iso-octane and 20% n-heptane by volume.
Correct answer: 20% n- heptane + 80% iso-octane- A. NH3
- B. CH4
- C. CO2
- D. C6H6
Explanation: Methane is the simplest alkane and has one carbon atom bonded to four hydrogen atoms, so its formula is CH4.
Correct answer: CH4- A. octane number
- B. Heptane number
- C. Reforming
- D. Refining
Explanation: Petrol quality for spark-ignition engines is expressed by its octane number, which measures resistance to knocking compared with standard…
Correct answer: octane number- A. Reforming
- B. Induction fueling
- C. Cracking
- D. Refining
Explanation: Cracking breaks large, less useful hydrocarbons into smaller hydrocarbons, including petrol-range molecules, so it increases the quantity…
Correct answer: Cracking- A. Coal Tar
- B. Coal gas
- C. Coke
- D. None of These
Explanation: Coke is the solid carbon-rich residue obtained by destructive distillation of coal and contains mostly carbon.
Correct answer: Coke- A. Refining
- B. Cracking
- C. Reforming
- D. None of These
Explanation: Catalytic reforming converts straight-chain hydrocarbons into branched, cyclic and aromatic hydrocarbons, which resist knocking and…
Correct answer: Reforming- A. Reforming
- B. Cracking
- C. Refining
- D. Isomerization
Explanation: Cracking is the thermal or catalytic decomposition of large hydrocarbon molecules into smaller alkanes and alkenes.
Correct answer: Cracking- A. Cracking
- B. Reforming
- C. Refining
- D. Hydration
Explanation: Reforming improves petrol quality by converting straight-chain hydrocarbons into branched, cyclic and aromatic compounds with better…
Correct answer: Reforming- A. Hydrogen & Water
- B. Hydrogen & Carbon dioxide
- C. Hydrogen & Methane
- D. Carbonmonoxdide & water
Explanation: Coal gas is produced by the destructive distillation of coal and contains hydrogen, methane, carbon monoxide and other gases, with…
Correct answer: Hydrogen & Methane- A. Methane
- B. Ethane
- C. Hydrogen
- D. Nitrogen
Explanation: Marsh gas is methane, CH4, because methane was historically collected from marshes during the decomposition of plant material under…
Correct answer: Methane- A. Petrol
- B. Sediment
- C. Rock
- D. Fuel
Explanation: The word petroleum comes from Latin roots: petra means rock and oleum means oil, giving the meaning “rock oil.” Therefore, petra refers to…
Correct answer: Rock