Hydrocarbon Test 6

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Question 1:

What is the name given to compounds with ________?





Topic: Classification of Organic Compounds

Correct Answer: C) Exactly two double bonds

Detailed Hint:
  • Answering this question correctly requires an understanding of organic compounds' nomenclature. Specifically, the names given to compounds based on the number of double bonds they possess.
  • Compounds with a single double bond are referred to as "alkenes", so option A does not fit.
  • Compounds with a triple bond are known as "alkynes", therefore option B is incorrect.
  • Compounds with more than two double bonds have different names based on their structure, ruling out option D.
  • Therefore, the correct answer is C - "Dienes" are compounds with exactly two double bonds.

Question 2:

Which statement best describes an optically active compound?





Topic: Optical Activity in Organic Compounds

Correct Answer: B) It influences the orientation of polarized light when in solution

Detailed Hint:
  • To answer this question, you need to understand what defines an optically active compound.
  • Optically active compounds are not defined by carbon content, so option A is incorrect.
  • The presence of an asymmetric carbon atom doesn't always lead to optical activity, hence option C isn't correct.
  • A negative reading on a polarimeter doesn't always indicate optical activity, leaving out option D.
  • Therefore, the correct answer is B - Optically active compounds can influence the orientation of polarized light when in solution, a characteristic known as optical isomerism.

Question 3:

What type of reaction is halogenation of alkanes?





Topic: Reaction mechanisms of Organic Compounds

Correct Answer: B) Free radical substitution

Detailed Hint:
  • Understanding the mechanisms of organic reactions is crucial here.
  • Halogenation of alkanes does not involve the replacement of a hydrogen atom with an electrophile; therefore, option A is incorrect.
  • Halogenation of alkanes does not involve a nucleophile replacing a leaving group; hence option C is incorrect.
  • Halogenation is not a reduction process, ruling out option D.
  • The correct answer is B - In a free radical substitution, a free radical replaces a hydrogen atom in the alkane, which is what happens in halogenation of alkanes.

Question 4:

What compound is commonly referred to as "Marsh Gas"?





Topic: Common Names of Organic Compounds

Correct Answer: B) Methane

Detailed Hint:
  • Knowledge of the common names of organic compounds is vital here.
  • Ethane, Propane, and Butane, options A, C, and D, are not known as "Marsh Gas".
  • Therefore, the correct answer is B - Methane, often found in marshy areas, is commonly referred to as "Marsh Gas".

Question 5:

What is the term for the process of converting n-hexane into benzene by heating in the presence of Pt?





Topic: Organic Chemistry Transformations

Correct Answer: B) Aromatization

Detailed Hint:
  • In order to answer this question, one must be familiar with different types of molecular transformations in organic chemistry.
  • Isomerization involves rearranging the atoms of a molecule to form an isomer, which does not describe the conversion of n-hexane to benzene. Therefore, option A is incorrect.
  • Dealkylation would involve the removal of an alkyl group from a molecule, which does not accurately describe this process. Hence, option C is incorrect.
  • While a rearrangement of atoms does occur in this reaction, the specific term for the conversion of an aliphatic compound (like n-hexane) to an aromatic compound (like benzene) is not simply "rearrangement". Thus, option D is incorrect.
  • The correct answer is B - This process is known as aromatization, where an aliphatic compound is converted into an aromatic compound.

Question 6:

Which of the following statements is not true about chiral compounds?





Topic: Stereochemistry and Chirality

Correct Answer: B) They have cis and trans isomers.

Detailed Hint:
  • Understanding the properties of chiral compounds is key to answering this question.
  • Chiral compounds do rotate the plane of polarized light, so option A is incorrect.
  • Chiral compounds can exist as enantiomers, therefore option C is incorrect.
  • The statement about chiral compounds having cis and trans isomers is false. Cis and trans isomerism is a type of geometric isomerism, not directly related to chirality, hence the correct answer is B.

Question 7:

What best describes the structure of benzene?





Topic: Resonance and Aromaticity

Correct Answer: C) It is a resonance hybrid of all 5 contributors.

Detailed Hint:
  • To correctly answer this question, you need to understand the concept of resonance and aromaticity in organic chemistry.
  • Benzene is not an equilibrium mixture of all 5 contributors; hence, option A is incorrect.
  • While Kekule's structures contribute to the resonance hybrid of benzene, the structure of benzene is not simply similar to two Kekule's structures, making option B incorrect.
  • A Dewar's structure is one possible contributing structure of benzene, but the true benzene structure is not simply similar to three of these, so option D is incorrect.
  • The correct answer is C - The structure of benzene is a resonance hybrid of all the contributing structures.

Question 8:

What is the end product of the hydrogenation of Butyne in the presence of a Na-Liq NH3 catalyst?





Topic: Alkyne Reduction

Correct Answer: A) Trans 2-Butene

Detailed Hints:
  • This question requires understanding of the process of hydrogenation of alkynes.
  • Hydrogenation of an alkyne results in an alkene. This rules out option D which suggests the formation of an alkane.
  • The catalyst Na-Liq NH3 favors trans addition, thus making the product Trans 2-Butene (Option A) correct.
  • Cis 2-Butene and 1-Butene are other possible products of alkyne hydrogenation, but not with this specific catalyst, so options B and C are incorrect.

Question 9:

What is the geometric structure of acetylene?





Topic: Molecular Geometry

Correct Answer: D) Linear

Detailed Hint:
  • To answer this question correctly, one needs to have a grasp of molecular geometrical structures.
  • Acetylene, an alkyne, has triple bonds which lead to a linear structure. Thus, option D is the correct answer.
  • Angular, bent, and trigonal structures are possible geometries for molecules, but not applicable for acetylene, so options A, B, and C are incorrect.

Question 10:

Which compound when electrolyzed, yields Ethane?





Topic: Electrolysis Reactions

Correct Answer: B) Potassium succinate

Detailed Hint:
  • This question requires knowledge of electrolysis reactions in organic compounds.
  • The process of Kolbe’s electrolysis involves the electrolysis of a carboxylic acid salt, resulting in the formation of an alkane.
  • Potassium succinate, when subjected to electrolysis, yields Ethane, making option B the correct answer.
  • The electrolysis of Potassium formate, acetate, and fumarate do not yield Ethane, thus making options A, C, and D incorrect.

Question 11:

Among these compounds, which one exhibits the highest reactivity?





Topic: Chemical Reactivity

Correct Answer: B) Ethene

Detailed Hint:
  • To tackle this question, you need to understand the reactivity of various hydrocarbons.
  • Ethene, an alkene, has a double bond that makes it more reactive than other options. Hence, option B is correct.
  • Benzene, Ethane, and Ethyne do not have the same level of reactivity as Ethene, ruling out options A, C, and D.

Question 12:

What is the most reliable method to distinguish between optical isomers?





Topic: Stereochemistry

Correct Answer: D) By polarimetry.

Detailed Hint:
  • This question tests your knowledge about the distinguishing techniques for optical isomers.
  • Polarimetry is the method used to distinguish between optical isomers as they rotate the plane polarized light in different directions. Therefore, option D is correct.
  • Chemical tests, Mass spectrometry, and IR spectroscopy are not as reliable for distinguishing between optical isomers, thus options A, B, and C are incorrect.

Question 13:

What catalyst is typically employed for Friedel Craft’s reactions?





Topic: Organic Reactions

Correct Answer: B) AlCl3

Detailed Hint:
  • Your knowledge of various catalysts used in organic reactions is tested in this question.
  • The Friedel Crafts reaction typically uses AlCl3 as a catalyst to introduce an alkyl group into the benzene ring. Thus, option B is correct.
  • HNO3, BeCl3, and FeCl3 are not typically used as catalysts in Friedel Craft’s reactions, hence options A, C, and D are incorrect.

Question 14:

Which of these compounds exhibits geometrical isomerism?





Topic: Isomerism

Correct Answer: B) Maleic acid

Detailed Hint:
  • This question evaluates your understanding of the concept of geometrical isomerism.
  • Geometrical isomers occur due to the restricted rotation about a double bond or a ring system. Maleic acid, with its double bond, exhibits geometrical isomerism, making option B the correct answer.
  • Lactic acid, I-Butane, and I.I-Dichloroethylene do not show geometrical isomerism, thus options A, C, and D are incorrect.

Question 15:

Which type of reaction leads to the replacement of an alkane's hydrogen with chlorine?





Topic: Organic Reactions

Correct Answer: C) Halogenation

Detailed Hint:
  • The question is about distinguishing different types of organic reactions.
  • Halogenation is the reaction in which a hydrogen atom in an alkane is substituted by a halogen atom, in this case, chlorine. Hence, option C is correct.
  • Hydrochloration, Hydroboration do not result in the replacement of hydrogen with chlorine in alkanes, ruling out options A and B. Option D is also incorrect.

Question 16:

How many possible isomers does xylene have?





Topic: Structural Isomerism

Correct Answer: B) 3

Detailed Hint:
  • Understanding the principle of structural isomerism is crucial to answer this question correctly.
  • Xylene, being a dimethylbenzene, has three possible isomers. Hence, option B is right.
  • The number of possible isomers is not 2, 4, or 5, hence options A, C, and D are incorrect.

Question 17:

How is the C=C bond in a compound's chain denoted?





Topic: Organic Chemistry Nomenclature

Correct Answer: B) By specifying the carbon atom number where the C=C bond begins.

Detailed Hint:
  • The question examines your understanding of organic chemistry nomenclature, particularly for compounds with C=C bonds.
  • According to IUPAC rules, the C=C bond is denoted by specifying the carbon atom number where the bond starts. Hence, option B is correct.
  • Options A, C, and D do not accurately represent the method of denoting a C=C bond in a compound's chain, making them incorrect choices.

Question 18:

Which substituent groups frequently associate with a benzene ring?





Topic: Aromatic Compounds

Correct Answer: A) Phenyl and benzyl

Detailed Hint:
  • This question tests your knowledge about the common substituents of aromatic compounds.
  • Phenyl and benzyl groups are typically associated with a benzene ring due to their structural similarities, despite the difference in a hydrogen atom. Thus, option A is correct.
  • Propyl, methyl, and butyl groups are not as commonly associated with a benzene ring as phenyl and benzyl, making options B, C, and D incorrect.

Question 19:

What is the ratio of Carbon to Hydrogen in aromatic hydrocarbons?





Topic: Hydrocarbon Ratios

Correct Answer: A) Low

Detailed Hint:
  • The question requires knowledge of the characteristics of different types of hydrocarbons, specifically aromatic hydrocarbons.
  • Aromatic hydrocarbons typically have a low Carbon to Hydrogen ratio, hence option A is the correct answer.
  • A high or equal Carbon to Hydrogen ratio is not characteristic of aromatic hydrocarbons, hence options B and C are incorrect. Option D is also not a valid option.

Question 20:

Which type of alcohol readily dehydrates to form alkenes?





Topic: Alcohol Dehydration

Correct Answer: C) Tertiary alcohol

Detailed Hint:
  • The question is about understanding the dehydration process of different types of alcohols.
  • Among primary, secondary, and tertiary alcohols, tertiary alcohols dehydrate easily because tertiary carbonium ions are stable and can easily lose the OH-group. So, option C is correct.
  • Primary and secondary alcohols do not dehydrate as easily as tertiary alcohols, ruling out options A and B. Option D is incorrect because not all types of alcohols dehydrate easily.

Question 21:

Who proposed the cyclic structure of benzene?





Topic: Organic Chemistry History

Correct Answer: D) Kekule

Detailed Hint:
  • This question tests your knowledge about the history of organic chemistry, particularly concerning the proposal of the benzene structure.
  • The cyclic structure of benzene was proposed independently by German chemists, Joseph Loschmidt and August Kekule von Stradonitz. Hence, option D is correct.
  • Dewar, Faraday, and Down did not propose the cyclic structure of benzene, making options A, B, and C incorrect.

Question 22:

When would a molecule be deemed chiral?





Topic: Chirality

Correct Answer: C) If it cannot be superimposed onto its mirror image.

Detailed Hint:
  • This question essentially tests your understanding of chirality in molecules.
  • A molecule is chiral if it cannot be superimposed onto its mirror image. Therefore, option C is the correct answer.
  • A molecule that contains a plane of symmetry or a center of symmetry or that can be superimposed onto its mirror image is not chiral, ruling out options A, B, and D.

Question 23:

What is the correct representation of a benzyl radical?





Topic: Benzyl Radicals

Correct Answer: C) C6H5 – CH2 –

Detailed Hint:
  • The question is about understanding the structure of the benzyl radical.
  • A benzyl radical is represented as C6H5 – CH2 –. Therefore, option C is correct.
  • The structures represented by options A, B, and D are not the benzyl radical, making them incorrect choices.

Question 24:

Which type of molecules affect plane polarized light?





Topic: Plane Polarized Light

Correct Answer: C) Chiral molecules

Detailed Hint:
  • The question revolves around the interaction of plane polarized light with different molecules.
  • Chiral molecules have the ability to affect plane polarized light, thereby making option C the correct answer.
  • Identical molecules, all polymers, and all biomolecules do not necessarily affect plane polarized light, making options A, B, and D incorrect.

Question 25:

Benzophenone is another name for:





Topic: Organic Compound Names

Correct Answer: C) Diphenyl Ketone

Detailed Hint:
  • This question tests your knowledge about the alternate names for different organic compounds.
  • Benzophenone is another name for Diphenyl Ketone, making option C the correct answer.
  • Biphenyl, Dimethyl Ketone, and Methyl phenyl Ketone are not alternate names for Benzophenone, making options A, B, and D incorrect.

Question 26:

What can be considered as a polymer of benzene?





Topic: Benzene and Polymers

Correct Answer: A) Ethyne

Detailed Hint:
  • This question is about understanding the concept of polymerization relating to the structure of benzene.
  • Ethyne, through a process known as trimerization, can form benzene, hence option A is the correct answer.
  • Ethene, Methane, and Ethane do not form benzene through polymerization, making options B, C, and D incorrect.

Question 27:

Which is the smallest alkane capable of forming a cycloalkane or ring structure?





Topic: Alkanes and Cycloalkanes

Correct Answer: C) Cyclopropane

Detailed Hint:
  • This question is about understanding the ability of small alkanes to form a cyclic structure or cycloalkane.
  • Out of the provided options, Cyclopropane is the smallest alkane that can form a successful cycloalkane structure. So, option C is correct.
  • Cyclomethane, Methane, and Propane cannot form a cycloalkane structure, ruling out options A, B, and D.

Question 28:

Which of the following compounds is not an open-chain or acyclic compound?





Topic: Cyclic and Acyclic Compounds

Correct Answer: C) Cyclopropane

Detailed Hint:
  • This question essentially tests your understanding of acyclic and cyclic compounds.
  • Cyclopropane is a cyclic compound and not an acyclic compound. Therefore, option C is the correct answer.
  • Acetaldehyde, Ethane, and Isobutane are acyclic compounds, ruling out options A, B, and D.

Question 29:

Who discovered Benzene and in what year?





Topic: History of Benzene

Correct Answer: C) Michael Faraday, 1825

Detailed Hint:
  • This question tests your knowledge about the history of the discovery of Benzene.
  • Benzene was discovered by Michael Faraday in 1825, so option C is the correct answer.
  • The years provided in options A, B, and D are not associated with the discovery of Benzene, making them incorrect choices.

Question 30:

At what angle are sp2 hybrid orbitals oriented in space?





Topic: Hybridization in Chemistry

Correct Answer: D) 120°

Detailed Hint:
  • This question checks your understanding about the concepts of hybridization in chemistry, particularly the sp2 hybridization.
  • The sp2 hybrid orbitals are oriented at an angle of 120° in space. Hence, option D is the correct answer.
  • The angles in options A, B, and C do not correspond to the orientation of sp2 hybrid orbitals, making them incorrect.

Question 31:

Which of the following is also known as Phthalic acid?





Topic: Organic Acids

Correct Answer: D) None of the above

Detailed Hint:
  • This question is about understanding the names of different organic acids.
  • None of the acids listed in options A, B, and C is also known as Phthalic acid. Hence, option D is correct.
  • The acids in options A, B, and C have distinct names and are not known as Phthalic acid, making them incorrect choices.

Question 32:

Which of the following is known as the first and simplest alkane?






Topic: Basic Hydrocarbons

Correct Answer: B) Methane

Detailed Hint:
  • This question is testing your basic understanding of hydrocarbons, specifically alkanes.
  • Methane, which is represented as CH4, is known to be the first and the simplest alkane. Therefore, option B is correct.
  • Ethane, C2H2, Methene, and CCl4 are not the first, nor the simplest alkanes, hence options A, C, D, and E are incorrect.

Question 33:

Which type of hybridization is possessed by the molecule of ethane?





Topic: Molecular Hybridization

Correct Answer: A) sp3

Detailed Hint:
  • The question assesses your comprehension of the concept of molecular hybridization, focusing on ethane.
  • Each carbon atom in the molecule of ethane is sp3 hybridized, making option A the correct answer.
  • sp2, sp, and None do not represent the correct hybridization type of an ethane molecule, ruling out options B, C, and D.

Question 34:

Which of these substances is not categorized as an alicyclic compound?





Topic: Categorizing Compounds

Correct Answer: D) Acetic acid

Detailed Hint:
  • This item examines your capacity to distinguish between various types of organic compounds, with a focus on alicyclic compounds.
  • Acetic acid is an acyclic or linear chain compound, indicating it does not belong in the category of alicyclic or ring compounds. Hence, option D is correct.
  • Cyclohexane, Cyclohexene, and Tetrahydrofuran are all examples of alicyclic compounds, making options A, B, and C incorrect.

Question 35:

Which is regarded as the simplest member of the aromatic hydrocarbons class?





Topic: Aromatic Hydrocarbons

Correct Answer: C) Benzene

Detailed Hint:
  • This question aims to examine your understanding of aromatic hydrocarbons, focusing on recognizing the simplest member of this class.
  • Benzene is known to be the simplest member of the aromatic hydrocarbons class, making option C the correct answer.
  • Methane and Alkane are not classified as aromatic hydrocarbons, and 'None of these' is not a valid choice in this context, ruling out options A, B, and D.
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