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 35 of 55
- A. 2-methyl hexane
- B. Neo-octane
- C. 5,5-dimethyl pentane
- D. 2,2-dimethyl hexane
Explanation: Condensed formula for 2,2 dimethyl hexane is CH3-(CH2)3-C(CH3)3. So, option D is the accurate answer.
Correct answer: 2,2-dimethyl hexane- A. n-pentane
- B. iso-pentane
- C. neo-pentane
- D. 2-methyl butane
Explanation: Neo-pentane (also known as 2,2-dimethylpropane) has the least melting and boiling points.
Correct answer: neo-pentane- A. 358.5
- B. 208
- C. 150.5
- D. 231.5
Explanation: The resonance hybrid structure of benzene is 150.5 KJ/mol more stable than the hypothetical 1,3,5-Cyclohexatriene due to the…
Correct answer: 150.5- A. Only occurs in organic compounds
- B. Not influenced by temperature
- C. Have same molecular formula
- D. Have different molecular formula
- E. Identical chemical properties
Explanation: Tautomers are a specific type of isomerism characterized by having the same molecular formula but differing in the connectivity of atoms…
Correct answer: Have same molecular formula- A. 0.80 g/cm³
- B. 0.88 g/cm³
- C. 0.85 g/cm³
- D. 0.82 g/cm³
- E. 0.08 g/cm³
Explanation: Benzene is a hydrocarbon with a density of approximately 0.879 g/cm³ at 20°C.
Correct answer: 0.88 g/cm³- A. Highest number of chloride atoms
- B. Lesser number of hydrogen atoms
- C. Highest number of hydrogen atoms
- D. Moderate number of hydrogen atoms
- E. Lesser number of chloride atoms
Explanation: This is based on Markovnikov's Rule, which states that in the addition of a protic acid (such as HCl, HBr, etc.) to an unsymmetrical…
Correct answer: Lesser number of hydrogen atoms- A. 1.34 Å
- B. 1.39 Å
- C. 1.56 Å
- D. 1.38 Å
- E. 1.46 Å
Explanation: Option B is correct because the bond length of C-C in benzene is approximately 1.39 Å.
Correct answer: 1.39 Å- A. Down Reduction
- B. Cope Reduction
- C. Wolff-Kishner Reduction
- D. Clemmensen reduction
- E. Sodium tetrahydroboride
Explanation: Clemmensen reduction is a chemical reaction used to convert carbonyl compounds (such as aldehydes and ketones) into alkanes.
Correct answer: Clemmensen reduction- A. Alkenes and alcohol
- B. Alkenes and cycloalkanes
- C. Alkanes and alkyl halides
- D. Alkenes and alkynes
- E. Alkanes and alkenes
Explanation: Alkenes are unsaturated hydrocarbons characterized by at least one carbon-carbon double bond (C=C) and have the general formula CₙH₂ₙ.
Correct answer: Alkenes and alkynes- A. functional group
- B. positional
- C. metamerism
- D. chain
Explanation: Position isomerism is a type of structural isomerism where compounds have the same molecular formula and the same functional group but…
Correct answer: positional- A. Chain
- B. Metamerism
- C. Geometric
- D. Tautomerism
Explanation: Geometric isomerism, also known as cis-trans isomerism, is a form of stereoisomerism where molecules have the same molecular formula but…
Correct answer: Geometric692. Which of the following is an example of substituent group which release electrons to benzene ring
- A. -CN
- B. -NR3+
- C. -NH2
- D. -NO2
Explanation: This group is an electron-donating group due to its ability to donate a lone pair of electrons to the benzene ring, increasing the…
Correct answer: -NH2693. In Friedel Craft acylation an acyl group is introduced in benzene ring in the presence of catalyst:
- A. AICl3
- B. H2SO4
- C. Sunlight
- D. V2O5
Explanation: The catalyst used in Friedel-Crafts acylation is typically Aluminum chloride (AlCl₃).
Correct answer: AICl3- A. 1:1
- B. 3:1
- C. 6:1
- D. 12:1
Explanation: The mass of carbon is 12g/mol and that of hydrogen is 1g/mol. Since there are 6 carbon atoms in benzene and 6 hydrogen atoms, the ratio of…
Correct answer: 12:1- A. 8
- B. 10
- C. 12
- D. 14
Explanation: C₃H₈ + 5O₂ → 3CO₂ + 4H₂OThis equation tells us that 1 mole of propane (C₃H₈) reacts with 5 moles of oxygen gas (O₂) .Since we have 2 moles…
Correct answer: 10- A. 2,2-Dimethypentane
- B. 2,2-Dimethypropane
- C. 2-Methy butane
- D. 3-Methylbutane
Explanation: The IUPAC name of 2,2-Dimethypropane is neopentane.
Correct answer: 2,2-Dimethypropane- A. Functional group isomers
- B. Geometrical isomers
- C. Optical isomers
- D. Position isomers
Explanation: Geometrical isomers, also known as cis-trans isomers or E-Z isomers, are a type of stereoisomerism that occurs due to the restricted…
Correct answer: Geometrical isomers- A. Cyclohexane
- B. Cyclohexene
- C. 1,3,5-cyclohexene
- D. 1,3,5-cyclohexatriene
Explanation: 1,3,5-Hexatriene is an open-chain conjugated diene that serves as a baseline to compare the stability of benzene due to its structure and…
Correct answer: 1,3,5-cyclohexatriene- A. Amphoteric
- B. Lewis's acid
- C. Lewis's base
- D. Transition metals
Explanation: A Lewis acid is defined as a substance that can accept an electron pair to form a covalent bond.
Correct answer: Lewis's acid- A. 5-Hexen-5-yne
- B. 2-Hexen-6-yne
- C. 4-Hexen-1-yne
- D. Hex-2-en-5-yne
Explanation: The correct IUPAC name for the compound СН3-CH=CH-CH2-C≡CH is 4-Hexen-1-yne.
Correct answer: 4-Hexen-1-yne