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 14 of 55
- A. C7H7
- B. C8H7
- C. C8H8
- D. C7H8
Explanation: Toluene has a molecular formula of C7H8. It consists of a benzene ring with a methyl group (-CH3) attached to it
Correct answer: C7H8- A. Hydrogen
- B. Oxygen
- C. Sulphur
- D. -OH
Explanation: In benzene sulfonic acid, the sulfonic group (-SO3H) is attached to the benzene ring through a sulfur atom
Correct answer: Sulphur- A. Two
- B. Three
- C. Four
- D. Five
Explanation: Phenanthrene is a fused polycyclic compound composed of three benzene rings, resulting in a total of four benzene rings when considering…
Correct answer: Three- A. 3
- B. 4
- C. 6
- D. 8
Explanation: Aniline is a derivative of benzene with an amino group (-NH2) attached to one of its carbon atoms.
Correct answer: 6- A. -NH2
- B. -CHO
- C. -COOH
- D. -CN
Explanation: In nomenclature, carboxylic acid (-COOH) is assigned the highest priority among the given groups
Correct answer: -COOH- A. Bromine
- B. Chlorine
- C. Fluorine
- D. Iodine
Explanation: When benzene is substituted by halogens, the priority for numbering the positions is given to the halogen with the higher atomic number.
Correct answer: Iodine- A. -CN
- B. -OH
- C. -COOH
- D. -CHO
Explanation: -OH (hydroxyl group) is not a meta-directing group. It is an ortho-para directing group in electrophilic aromatic substitution reactions
Correct answer: -OH- A. -OH, -RCO
- B. -NR3, -CN
- C. -OCH3, -CHO
- D. -N(CH3)2, -NH2
Explanation: Both -OH and -RCO (carbonyl group) are ortho-para directing groups in electrophilic aromatic substitution reactions
Correct answer: -OH, -RCO- A. Specific gravity method
- B. Distillation method
- C. X-ray diffraction method
- D. both a and b
Explanation: The molecular mass of benzene (C6H6) was determined using the X-ray diffraction method.
Correct answer: X-ray diffraction method- A. Four
- B. Three
- C. Six
- D. One
Explanation: When benzene is heated with hydrogen in the presence of platinum, three moles of hydrogen are added to benzene to form cyclohexane.
Correct answer: Three- A. Benzyl chloride
- B. o-chlorotoluene
- C. p-chlorotoluene
- D. Benzoic acid
Explanation: Chlorination of toluene in the presence of sunlight produces
Correct answer: Benzyl chloride- A. -239 kJ/mol
- B. -208 kJ/mol
- C. -19.5 kJ/mol
- D. Kcal/mol
Explanation: Hydrogenation of cyclohexene involves breaking a pi bond and forming two new sigma bonds.
Correct answer: -208 kJ/mol- A. Acetylene
- B. n-hexane
- C. Benzene sulphonic acid
- D. Sodium benzoate
Explanation: The mixture of catalysts Cr2O3 + Al2O3 + SiO2 is used when benzene is produced from acetylene at elevated temperatures (500°C).The mixture…
Correct answer: Acetylene- A. Diphenyl amine
- B. Naphthalene
- C. Diphenyl methane
- D. Biphenyl
Explanation: Naphthalene is a fused cyclic aromatic compound. It consists of two benzene rings fused together.
Correct answer: Naphthalene- A. Strong nucleophile
- B. Weak nucleophile
- C. Strong electrophile
- D. Weak electrophile
Explanation: In Friedel-Crafts alkylation, AlCl3 serves as a Lewis acid catalyst that reacts with the alkyl halide to form a carbocation, which is a…
Correct answer: Strong electrophile- A. RCOO
- B. COCl
- C. RCO
- D. HCO
Explanation: Acylation of benzene involves the introduction of an acyl group (RCO) onto the benzene ring.
Correct answer: RCO- A. Benzene
- B. Nitrobenzene
- C. Toluene
- D. Dichlorobenzene
Explanation: Nitrobenzene readily undergoes sulphonation due to the presence of the nitro group (-NO2), which is a strong activating group directing…
Correct answer: Nitrobenzene- A. On hydrogenation, 208 KJ/mole is liberated.
- B. C-H bond length in benzene is 1.09 Å
- C. Molecular mass of benzene is 78.108
- D. Resonance energy of benzene 150.5 kcal/mole
Explanation: Benzene does not undergo typical hydrogenation reactions like alkenes do.
Correct answer: On hydrogenation, 208 KJ/mole is liberated.279. What is required other than anhydrous AlCl3 when toluene is produced in Friedel-Crafts reaction?
- A. C6H6
- B. C6H6 + CH3Cl
- C. C6H5C2H5
- D. C6H5Cl & CH3Cl
Explanation: In Friedel-Crafts alkylation, toluene is produced by the reaction of benzene (C6H6) with an alkyl halide (CH3Cl) in the presence of…
Correct answer: C6H6 + CH3Cl280. Replacement of hydrogen of benzene by alkyl group in the halide & aluminum chloride is known as
- A. Dow's process
- B. Friedel & Craft acylation
- C. Friedel & Craft alkylation
- D. Clemmenson reduction
Explanation: The replacement of a hydrogen atom of benzene by an alkyl group using a halide and aluminum chloride as a catalyst is known as…
Correct answer: Friedel & Craft alkylation