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 41 of 55
- A. -119.5 kJ/mol
- B. -358.5 kJ/mol
- C. +150.5 kJ/mol
- D. -208 kJ/mol
Explanation: Resonance energy is the difference between the actual enthalpy of hydrogenation of benzene (-208 kJ/mol) and the theoretical enthalpy…
Correct answer: +150.5 kJ/mol- A. One of the products exists as three stereoisomers
- B. Two pairs of diastereomers are obtained only
- C. Only one meso stereoisomer is obtained
- D. Two pairs of enantiomers are obtained
Explanation: The correct answer is Option D: Two pairs of enantiomers are obtained because enantiomers come in pairs and a single compound cannot form…
Correct answer: Two pairs of enantiomers are obtained- A. Bromine water test
- B. Hydroxylation
- C. Ozonolysis
- D. Both "A" and "B"
Explanation: When differentiating between an alkane and an alkene, it is important to consider their saturation levels.
Correct answer: Both "A" and "B"- A. They have high percentage of hydrogen
- B. They have a ring structure
- C. They have high percentage of carbon
- D. They resist in reaction with air
Explanation: Aromatic compounds burn with a sooty flame because the benzene rings in their structure resist complete combustion, leading to the…
Correct answer: They have high percentage of carbon- A. Introduction of R-group in the benzene ring in the presence of AlCl3 is called alkylation
- B. Introduction of acyl group in the benzene ring in the presence of AlCl3 is called acylation
- C. Benzene cannot undergo polymerization
- D. Ozonolysis of benzene results in the formation of (COOH)2
Explanation: The correct answer is option D. Ozonolysis of benzene does not result in the formation of (COOH)2, but rather produces glyoxal as the…
Correct answer: Ozonolysis of benzene results in the formation of (COOH)2- A. Saturated hydrocarbons
- B. Unsaturated hydrocarbon
- C. Both of above
- D. None ofthese
Explanation: Alkanes are indeed known as saturated hydrocarbons because they contain only single bonds between carbon atoms, meaning they have the…
Correct answer: Saturated hydrocarbons- A. Peroxide effect
- B. Markovnikov's rule
- C. Anti markovnikov's rule
- D. Kharish effects
Explanation: Markovnikov's Rule dictates the addition of hydrogen bromide to an unsymmetrical alkene, where the hydrogen attaches to the carbon with…
Correct answer: Markovnikov's rule- A. C6H6O9
- B. C6H5O8
- C. C6H6O6
- D. C6H6O7
Explanation: Benzenetriozonide is formed when benzene reacts with ozone, resulting in the molecular formula C6H6O9.
Correct answer: C6H6O9- A. Three
- B. Four
- C. Six
- D. Eight
Explanation: Benzene is a planar molecule with a hexagonal ring of carbon atoms and alternating double bonds.
Correct answer: Six- A. Benzaldehyde
- B. Glyoxal
- C. Glyoxime
- D. Glycol
Explanation: The hydrolysis of benzenetriazolide will yield three moles of glyoxal. The reaction is shown below:C6H5N3C6H5 + 6H2O ?
Correct answer: Glyoxal- A. C6H6 + CH3Cl
- B. C6H6
- C. C6H5C2H5
- D. C6H5Cl & CH3Cl
Explanation: In the Friedel-Crafts alkylation reaction to prepare toluene, anhydrous aluminum chloride (AlCl3) acts as a catalyst.
Correct answer: C6H6 + CH3Cl- A. HSO-
- B. SO2
- C. SO3
- D. H+
Explanation: The electrophile generated during the sulfonation of benzene by H2SO4 is SO3.
Correct answer: SO3- A. C3H7O-
- B. SCN-
- C. H2C+
- D. NH3
Explanation: H2C+ is a carbocation, which is an electron-deficient species i.e. an electrophile.
Correct answer: H2C+- A. Addition
- B. Elimination
- C. Free radical substitution
- D. Nucleophilic substitution
Explanation: Free radical substitution) - Correct: Halogenation of alkanes follows a free radical chain mechanism, initiated by UV light.
Correct answer: Free radical substitution- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: The reactivity of alkenes towards the addition of bromine can be determined by the presence of electron-donating or electron-withdrawing…
Correct answer: Option C- A. Pentene >butene>propene
- B. Butene>ethene>propyne
- C. Propene>butene> pentene
- D. None of these
Explanation: Reactivity of alkenes is inversely proportional to the no. of carbon atoms. As the no.
Correct answer: Propene>butene> pentene- A. Both are highly ionic
- B. One is oxidising and the other is reducing
- C. One of the step is endothermic in both the cases
- D. All the steps are exothermic in both the cases
Explanation: HI and HCl do not do this for energetic reasons. The addition of Cl and I radicals to alkanes in an anti-Markovnikov fashion is an…
Correct answer: One of the step is endothermic in both the cases- A. Hydrolysis of phenyl magnesium iodide - Benzene
- B. y- Isomer BHC - Lindane
- C. (4n+2)pie rule - Aromaticity
- D. Trimerisation of propyne - Mesitylene
Explanation: Option A suggests that hydrolysis of phenyl magnesium iodide results in the formation of benzene. However, this is not correct.
Correct answer: Hydrolysis of phenyl magnesium iodide - Benzene- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: The rate of Hydrogenation of an alkene decreases with increasing alkyl substitution on C = C.21.
Correct answer: Option A- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: Attack of Br0 free radical on tertiary carbon is thermodynamically more favoured, leading to the formation of tertiary free radical, which…
Correct answer: Option B