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.
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Read the Chemistry of Hydrocarbons notesFree MDCAT chapter notes with key terms1,091 questions · page 7 of 55
- A. Cr2O3 + A2O3 + SiO2
- B. Raney nickel
- C. Organo-nickel
- D. Ni 250 - 300°C
Explanation: At about 70°C, acetylene can undergo cyclotrimerisation to form benzene in the presence of an organo-nickel catalyst.
Correct answer: Organo-nickel- A. 150.5 kJ/mol
- B. 250.5 kJ/mol
- C. 150.5 Cal/mol
- D. 250.5 Cal/mol
Explanation: The resonance energy of benzene is approximately 150.5 kJ/mol, representing the extra stability caused by delocalisation of its pi…
Correct answer: 150.5 kJ/mol123. How many moles of H2 are added up when benzene is heated with hydrogen in the presence of platinum ?
- A. Two
- B. Three
- C. Four
- D. Six
Explanation: Complete catalytic hydrogenation converts benzene, C6H6, into cyclohexane, C6H12: C6H6 + 3H2 -> C6H12.
Correct answer: Three- A. The presence of Oxygen
- B. The presence of Hydrogen
- C. The absence of Oxygen
- D. The presence of excessive Oxygen
Explanation: Destructive distillation heats vegetable oil strongly in the absence of oxygen, causing decomposition into smaller substances including…
Correct answer: The absence of Oxygen- A. 3
- B. 4
- C. 6
- D. 8
Explanation: Each of benzene's three p orbitals contributes a pair of pi electrons to the delocalised electron cloud, giving 3 x 2 = 6 delocalised…
Correct answer: 6- A. Two
- B. Three
- C. Four
- D. Five
Explanation: Phenanthrene is made of three fused benzene rings arranged in an angular structure.
Correct answer: Three- A. Aliphatic
- B. Alicyclic
- C. Aromatic
- D. Aldehyde
Explanation: Aromatic hydrocarbons have a relatively high carbon-to-hydrogen ratio, so incomplete combustion often produces glowing carbon particles…
Correct answer: Aromatic- A. Chlorobenzene
- B. Toluene
- C. Nitrobenzene
- D. Benzene
Explanation: The methyl group in toluene releases electron density into the benzene ring by induction and hyperconjugation, activating it towards…
Correct answer: Toluene- A. Phenol
- B. Maleic anhydride
- C. Glyoxal
- D. Benzoic acid
Explanation: Vapour-phase oxidation of benzene with air over V2O5 at about 450°C cleaves the ring and produces maleic anhydride.
Correct answer: Maleic anhydride- A. fats
- B. resins
- C. iodine
- D. all the above
Explanation: Benzene is a non-polar organic solvent, so it dissolves largely non-polar substances such as fats, many resins and iodine.
Correct answer: all the above- A. I2>Cl2>Br2>F2
- B. F2>Cl2>I2>Br2
- C. F2>Cl2>Br2>I2
- D. Cl2>F2>Br2>I2
Explanation: The ease of halogenation follows F2 > Cl2 > Br2 > I2 because fluorination is extremely rapid and iodination is generally unfavourable…
Correct answer: F2>Cl2>Br2>I2- A. Benzyl chloride
- B. o - chlorotoluene
- C. p - chlorotoluene
- D. benzoic acid
Explanation: In sunlight, chlorine forms radicals that substitute a hydrogen atom at the benzylic position of toluene, producing benzyl chloride…
Correct answer: Benzyl chloride- A. Benzy1 chloride
- B. Benzal dichloride
- C. O-chlorotoluene
- D. O-chlorotoluene and P-chlorotoluene
Explanation: In sunlight, chlorine forms radicals and preferentially replaces a hydrogen at the benzylic position of toluene, producing benzyl…
Correct answer: Benzy1 chloride- A. Substitution reaction
- B. Elimination reaction
- C. Addition reaction
- D. Condensation reaction
Explanation: Catalytic hydrogenation of alkenes exhibits addition reactions. Addition reactions in an unsaturated compound mean a compound that has a…
Correct answer: Addition reaction- A. Cyclohexane
- B. Heterocyclic
- C. Alicyclic
- D. Unsaturated aliphatic
Explanation: Reduction of benzene in the presence of nickel (Ni) results in the formation of cyclohexane.
Correct answer: Cyclohexane- A. Alkenes
- B. Alkynes
- C. Alkanes
- D. Benzene
Explanation: Both alkenes and cycloalkanes have general formula CnH2n.
Correct answer: Alkenes- A. Butane
- B. Propane
- C. Pentane
- D. Hexane
Explanation: In the Wurtz reaction, two alkyl halides react with sodium to form a higher alkane.
Correct answer: Propane- A. Cannizaro's reaction
- B. Kolbe's reaction
- C. Sabatier & Senderen's reaction
- D. Wurtz reaction
Explanation: Option D is correct as the Wurtz reaction is an organic chemical coupling reaction wherein sodium metal is reacted with two alkyl halides…
Correct answer: Wurtz reaction- A. 3,3 4- trimethyl hexane
- B. 1,1,2- trimethyl ethane
- C. 2,2-dimethyl propane
- D. 2-ethyl,1-methylethane
Explanation: To name this first identity the longest carbon chain is 6-carbon long. Hence the name should include hexane, which is A.
Correct answer: 3,3 4- trimethyl hexane- A. Mixture of SiO2 and Ni
- B. Mixture of Pt and Cu
- C. Mixture of Fe and MgO
- D. Mixture of SiO2 and Al2O3
Explanation: A typical catalyst used for this purpose is a mixture of silica (SiO2) and alumina (AI2O3). So this is correct answer.
Correct answer: Mixture of SiO2 and Al2O3