Q1.Select the nucleophile from the following examples:
- A.NO₂
- B.NH₃
- C.NO₂⁺
- D.N⁺H₄
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Correct answer: B. NH₃
Ammonia (NH3), with a lone pair of electrons on nitrogen available for donation, acts as a nucleophile in chemical reactions.
Organic Chemistry Basics MCQs for MDCAT
64 practice MCQs on functional groups, IUPAC nomenclature, isomerism, alkyl halides, amines and polymers. Every question has the correct answer and an explanation.
Start free — 20 questionsOrganic Chemistry Basics is part of the MDCAT Chemistry syllabus. This page collects Organic Chemistry Basics MCQs in the style of past MDCAT papers — below are 12 of them with answers and explanations, and the full set of 64 questions is in the HighYield MDCAT QBank.
This chapter covers: functional groups, IUPAC nomenclature, isomerism, alkyl halides, amines and polymers.
Organic Chemistry Basics MCQs with answers
Q2.Which one of the following is NOT a nucleophile:
- A.NH₂⁻
- B.H₂O
- C.BF₃
- D.CH₃⁻
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Correct answer: C. BF₃
BF3, an electron-deficient Lewis acid lacking a lone pair to donate, is not a nucleophile — unlike NH2-, H2O and CH3-, which all have lone pairs (or negative charge) available to donate.
Q3.Organic compound containing both amine and carboxyl group is known as
- A.Amino acid
- B.Fatty acid
- C.Saccharide
- D.Amide
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Correct answer: A. Amino acid
A compound containing both an amine and a carboxyl functional group is classified as an amino acid.
Q4.Indicate the cyclic amino acid from the following:
- A.Cysteine
- B.Serine
- C.Haloamine
- D.Proline
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Correct answer: D. Proline
Proline is the cyclic amino acid among these options, with its amino group forming part of a five-membered ring structure.
Q5.When hexane dioic acid is heated with hexamethylene diamine, the compound formed is:
- A.Polypeptide
- B.Addition polymer
- C.Ester
- D.Nylon 6,6
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Correct answer: D. Nylon 6,6
Heating hexanedioic acid (adipic acid) with hexamethylenediamine in a condensation reaction produces the polyamide Nylon 6,6.
Q6.Both ribose and deoxyribose are monosaccharides containing ___ carbon atoms.
- A.Four
- B.Six
- C.Five
- D.Seven
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Correct answer: C. Five
Ribose and deoxyribose are both pentose sugars, containing five carbon atoms, forming the sugar backbone of RNA and DNA respectively.
Q7.Out of these which nitrogen base is NOT present in DNA?
- A.Adenine
- B.Guanine
- C.Uracil
- D.Thymine
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Correct answer: C. Uracil
Uracil is not present in DNA; it is found in RNA instead, where it replaces thymine to pair with adenine.
Q8.In the woody parts of trees, the %age of cellulose is:
- A.50%
- B.10%
- C.30%
- D.100%
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Correct answer: D. 100%
Cellulose makes up approximately 50% of the material in the woody parts of trees, forming the main structural component of wood.
Q9.Acctamide is prepared by heating:
- A.Ammonium acetate
- B.Methyl cyanide
- C.Ethyl acetate
- D.Ethyl cyanide
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Correct answer: A. Ammonium acetate
Carboxylic acids react with ammonia to form ammonium salts which on heating produce acid amides.
Q10.Which of the functional groups are present in ethyl acetate?
- A.Aldehyde group
- B.Carboxyl group
- C.Ester group
- D.Ether group
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Correct answer: C. Ester group
The ester group is present in ethyl acetate. Ester groups consist of a carbonyl group (C=O) bonded to an oxygen atom, which is further bonded to an alkyl or aryl group. In ethyl acetate, the ester group consists of the carbonyl group bonded to an oxygen atom, which is further bonded to an ethyl group.
Q11.Amino acids mainly differ from each other by the difference in their:
- A.R-group
- B.Amino group
- C.Carboxyl group
- D.Hydrogen of alpha carbon
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Correct answer: A. R-group
Option A is correct.Amino acids mainly differ from each other by the difference in their R-group. The R-group is a side chain that is attached to the alpha carbon of an amino acid. The R-group can be any of 20 different functional groups, which is what gives different amino acids their unique properties. The other options are all common to all amino acids:All amino acids have an amino group (-NH2) attached to their alpha carbon. All amino acids have a carboxyl group (-COOH) attached to their alpha carbon. All amino acids have a hydrogen atom attached to their alpha carbon.
Q12.The correct order of reactivity of alkyl halides is.
- A.R-Br > R-CL > R-F > R-I
- B.R-Br > R-F > R-I > R-CI
- C.R-I > R-Br > R-Cl > R-F
- D.R-Cl > R-I > R-Br > R-F
Show answer
Correct answer: C. R-I > R-Br > R-Cl > R-F
The reactivity of alkyl halides towards nucleophilic substitution reactions follows the order:R-I (alkyl iodide) > R-Br (alkyl bromide) > R-Cl (alkyl chloride) > R-F (alkyl fluoride)This order is based on the strength of the carbon-halogen bond, with the weaker bonds being more reactive. The bond strength decreases from R-F (strongest) to R-I (weakest), making R-I the most reactive and R-F the least reactive
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