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Free Fundamental Principles of Organic Chemistry MCQs with Answers

536 Fundamental Principles of Organic Chemistry MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

Organic chemistry begins with carbon compounds classified by carbon skeleton, saturation and functional group. Work includes identifying groups such as hydroxyl, carbonyl, carboxyl and amino, applying basic nomenclature, and distinguishing structural, geometric and optical isomers, where the same molecular formula does not necessarily mean the same structure or properties.

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Classification of Organic CompoundsFunctional GroupsIsomerism
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536 questions · page 21 of 27

401. Identify the compound that does not exhibits tautomerism:-

  • A. 2-Pentanone
  • B. Phenol
  • C. 2-Butene
  • D. Lactic acid

Explanation: A Reaction which involves simple proton transfer in an intramoleculer fashion is called tautomerism.Hence lactic acid,phenol,2-pentanone…

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Correct answer: 2-Butene

402. Which of the following compounds will exhibit cis-trans (isomerism) choose which one is correct:

  • A. Butanal
  • B. 2-butyne
  • C. 2-butanol
  • D. 2- butene

Explanation: Only compounds with a double bond and atleast 2 different substituents on either side can exhibit cis-trans isomerism.

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Correct answer: 2- butene

403. Five carbon compounds, pentane has number of isomers:

  • A. Five
  • B. Four
  • C. Three
  • D. One

Explanation: Pentane is an alkane with five carbon atoms.It has three Constitutional isomers,shown below: Reference:google.

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Correct answer: Three

404. Number of isomers of butane (C4H10):

  • A. 1
  • B. 2
  • C. 3
  • D. 4

Explanation: Butane has two structural isomers: Normal butane also known as unbranched butane,and Isobutane,commonly known as i-butane.

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Correct answer: 2

405. Compounds having same molecular formula but different structural formula are called as

  • A. Polymer
  • B. Monomer
  • C. Isomers
  • D. Allotropes

Explanation: The compounds having same molecular formula but different structural formula are called as isomers.

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Correct answer: Isomers

406. Consider the following condensed formula of alkane:(CH3)2CH(CH2)-C(CH3)3The correct name of the above formula according to IUPAC is:

  • A. 2,3,4-Trimethylpentane
  • B. 2,6,6-Trimethylpentane
  • C. 2,4,4-Trimethylpentane
  • D. 2,2,4-Trimethylpentane

Explanation: According to this name, there are three methyl groups attached to carbon atoms, two on 2nd carbon atom and one on 4th carbon atom of the…

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Correct answer: 2,2,4-Trimethylpentane

407. Which of the following is aromatic?

  • A. Anthracene
  • B. Naphthalene
  • C. Phenol
  • D. All of the above

Explanation: All of these compounds possess aromatic ring structures, making them aromatic compounds.

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Correct answer: All of the above

408. Which of the following is not aromatic?

  • A. Anthracene
  • B. Naphthalene
  • C. Phenol
  • D. None of these

Explanation: Option d implies that all of the compounds listed (Anthracene, Naphthalene, and Phenol) are aromatic, which is correct.

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Correct answer: None of these

409. Alicyclic compounds are similar in properties to:

  • A. Heterocyclic compounds
  • B. Aliphatic compounds
  • C. Acyclic compounds
  • D. Aromatic compounds

Explanation: The behavior of alicyclic compounds is similar to those of aliphatic compounds.

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Correct answer: Aliphatic compounds

410. In this section of logical deduction, the question consists of a brief passage (usually a report containing certain data regarding some social or economic problem), followed by certain inferences based on it. The student is required to analyze the contents (or data) of the passage and grasp the desirable facts from it. Then, student has to consider each of the given inferences in the context of the given passage. decide upon its degree of truth or falsity and then choose the hest alternative provided accordingly. Though the State cultivates only 3.2 lakh tons of mangoes. they are of premium quality and with mangoes becoming second most consumed fruit in the world after grapes, the government has been trying exporting it through sea route which is cheaper. An experiment which was done in this regard last year hasred successful. The State also cultivates a large number of medium quality of mangoes.

  • A. Definitely true
  • B. Probably true
  • C. Data inadequate
  • D. Probably false
  • E. Definitely false

Explanation: Based on the given passage, the following inferences can be made: The State exports mangoes through the sea route: True The passage…

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Correct answer: Probably true

411. In the following question, two statements numbered I and II are given. There may be cause and effect relationship between the two statements. These two statements may be the effect of the same cause or independent causes. These statements may be independent causes without saving any relationship. Read both the statements in question and mark your answer as:A. If statement I is the cause and statement II is its effect;B. If statement II is the cause and statement, I is its effect;C. If both the statements I and II are independent causes;D. If both the statements I and II are effects of independent causes;E. If both the statements I and II are effects of some common causes;I. The middle-class society has improved their quality of living constantly in the last few years.II. Economical standards in Pakistan is improving remarkably.

  • A. A. If statement I is the cause and statement II is its effect;
  • B. B. If statement II is the cause and statement I is its effect;
  • C. C. If both the statements I and II are independent causes;
  • D. D. If both the statements I and II are effects of independent causes;
  • E. E. If both the statements I and II are effects of some common cause;

Explanation: Option B is correct.If Pakistan's economic standards improve, then naturally the middle-class quality of living improves.

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Correct answer: B. If statement II is the cause and statement I is its effect;

412. In the following question, two statements numbered I and II are given. There may be cause and effect relationship between the two statements. These two statements may be the effect of the same cause or independent causes. These statements may be independent causes without saving any relationship. Read both the statements in question and mark your answer as:A. If statement I is the cause and statement II is its effect;B. If statement II is the cause and statement, I is its effect;C. If both the statements I and II are independent causes;D. If both the statements I and II are effects of independent causes;E. If both the statements I and II are effects of some common causes;I. The government has taken the new initiafive in which the fee charged by the unaided institutions has been reduced as compared to last year.II. The students have protested against the high fee last year.

  • A. A. If statement I is the cause and statement II is its effect;
  • B. B. If statement II is the cause and statement I is its effect;
  • C. C. If both the statements I and II are independent causes;
  • D. D. If both the statements I and II are effects of independent causes;
  • E. E. If both the statements I and II are effects of some common causes;

Explanation: The correct answer is B. Statement II is the cause, and statement I is its effect.

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Correct answer: B. If statement II is the cause and statement I is its effect;

413. Passage: Three persons A, B and C wore shirts of black, blue and orange colours (not necessarily in that order) and pants of green, yellow and orange colours (not necessarily in that order). No person wore pant and shirt of the same colour. A did not wear shirt of black colour. B did not wear shirt of blue colour. C did not wear shirt of orange colour. A did not wear pant of green colour. B wore pant of orange colour. What were the colours of pant and shirt worn by C, respectively?

  • A. Yellow and black
  • B. Yellow and blue
  • C. Green and blue
  • D. Orange and black

Explanation: From the clues, we can deduce the combinations. Since B wore orange pants, A and C must have worn green and yellow pants.

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Correct answer: Green and blue

414. Which of the following is an amide?

  • A. (NH2)2CO
  • B. NH2CH3
  • C. C6H5NH2
  • D. N(CH3)3

Explanation: Urea is organic compound which belongs to amide class

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Correct answer: (NH2)2CO

415. Which of the following statements is incorrect?

  • A. Catenation is the main reason for large number of organic compounds
  • B. The higher is the octane number, the better is quality of the petrol
  • C. Reforming is done to increase the production of petrol
  • D. Anthracite is the hardest form of coal

Explanation: Reforming is a process used in petroleum refining to convert low-octane hydrocarbons into high-octane hydrocarbons.

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Correct answer: Reforming is done to increase the production of petrol

416. n-Heptane can be converted into benzene by catalysts:

  • A. Al2O3, SiO2, Fe2O3
  • B. SiO2, K2O, Cr2O3
  • C. Al2O3, SiO2, Cr2O3
  • D. None of these

Explanation: The conversion of n-heptane to benzene is a process called aromatization. This involves the cyclic dehydrogenation of alkanes.

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Correct answer: Al2O3, SiO2, Cr2O3

417. How many Dewar Structure of Benzene are present?

  • A. 2
  • B. -3
  • C. 3
  • D. 4

Explanation: The Dewar structure is an isomer of benzene where the six-membered ring is not planar and has a fused cyclobutene ring.

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Correct answer: 3

418. Alicyclic hydrocarbons will not follow _ general formula.

  • A. CnH2n
  • B. CnH2n-2
  • C. CnH2n+2
  • D. C2H2n-4

Explanation: The general formula CnH2n+2 is characteristic of saturated, open-chain hydrocarbons (alkanes).

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Correct answer: CnH2n+2

419. Fractions of crude petroleum can be obtained by using _?

  • A. Destructive distillation
  • B. Fractional distillation
  • C. Vacuum distillation
  • D. Dry distillation

Explanation: Fractional distillation is the industrial process used to separate crude oil into its various components, or fractions.

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Correct answer: Fractional distillation

420. All of the following are polar organic compounds EXCEPT:

  • A. C10H22
  • B. CH3CHO
  • C. CHCl3
  • D. CH3CH2OH

Explanation: C10H22 is non-polar organic compound. In fact, it is example of alkane. Its name is decane.

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Correct answer: C10H22
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