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Organic Chemistry – Some Basic Principles and Techniques MCQs

Class 11 Chemistry — questions with answers and worked explanations.

20 free questions Class 11 Chemistry Answers + explanations No sign-up

These questions are drawn from the Pariksha Sutra question bank for Organic Chemistry – Some Basic Principles and Techniques, part of the Class 11 Chemistry syllabus. Each one shows the correct answer and, where a method helps, the working behind it.

Read the question, decide your answer before looking, then check the explanation — that is what turns practice into marks. If a question catches you out, the explanation is the part worth re-reading.

Questions

Question 1
The shape of methane (CH4) molecule is:
  1. Square planar
  2. Pyramidal
  3. Trigonal planar
  4. Tetrahedral
Answer: Tetrahedral
Question 2
Benzene belongs to which class of organic compounds?
  1. Aromatic
  2. Alicyclic
  3. Aliphatic saturated
  4. Acyclic
Answer: Aromatic
Question 3
The IUPAC name of CH3-CH2-CH2-CH3 is:
  1. Propane
  2. Butane
  3. Isobutane
  4. Pentane
Answer: Butane
Question 4
The IUPAC name of CH3-CH2-CH2-NH2 is:
  1. Propan-1-amine
  2. Propanamide
  3. Propan-1-ol
  4. Propanenitrile
Answer: Propan-1-amine
Question 5
In the bond-line notation of a compound, hydrogen atoms attached to carbon are:
  1. Drawn explicitly
  2. Shown as circles
  3. Shown as dots
  4. Not drawn but assumed
Answer: Not drawn but assumed
Question 6
An equimolar mixture of two enantiomers that is optically inactive is called a:
  1. Diastereomer mixture
  2. Racemic mixture
  3. Conformer
  4. Meso compound
Answer: Racemic mixture
Question 7
The correct order of stability of carbocations is:
  1. 3° > 2° > 1° > methyl
  2. 2° > 3° > methyl > 1°
  3. 1° > 2° > 3° > methyl
  4. methyl > 1° > 2° > 3°
Answer: 3° > 2° > 1° > methyl
Question 8
Which of the following species can act as a nucleophile?
  1. OH-
  2. AlCl3
  3. H+
  4. BF3
Answer: OH-
Question 9
As s-character increases in a hybrid orbital, the C-H bond length:
  1. Decreases
  2. Remains unchanged
  3. First increases then decreases
  4. Increases
Answer: Decreases
Question 10
Compounds with the same functional group and similar chemical properties form a:
  1. Resonance hybrid
  2. Racemic mixture
  3. Homologous series
  4. Conformation set
Answer: Homologous series
Question 11
The IUPAC name of CH2=CH-CH2-CH3 is:
  1. But-1-yne
  2. But-2-ene
  3. But-1-ene
  4. Butane
Answer: But-1-ene
Question 12
The condensed structural formula (CH3)2CHCH3 corresponds to:
  1. 2-Methylpropane
  2. Butane
  3. 2-Methylbutane
  4. Propane
Answer: 2-Methylpropane
Question 13
CH3-O-CH2-CH2-CH3 and CH3-CH2-O-CH2-CH3 are examples of:
  1. Optical isomers
  2. Chain isomers
  3. Functional isomers
  4. Metamers
Answer: Metamers
Question 14
How many alpha C-H bonds are available for hyperconjugation in the tert-butyl carbocation (CH3)3C+ ?
  1. 3
  2. 6
  3. 12
  4. 9
Answer: 9
Question 15
In reaction mechanisms, a single-barbed (half-headed) curved arrow represents the movement of:
  1. A proton
  2. A whole atom
  3. A pair of electrons
  4. One electron
Answer: One electron
Question 16
Crystallisation as a purification method is based on the difference in:
  1. Solubility of the compound and impurity in a solvent
  2. Densities of the components
  3. Colours of the components
  4. Boiling points of components
Answer: Solubility of the compound and impurity in a solvent
Question 17
The H-C-H bond angle in methane is approximately:
  1. 120 degrees
  2. 180 degrees
  3. 109.5 degrees
  4. 90 degrees
Answer: 109.5 degrees
Question 18
Cyclohexane is best classified as a(n):
  1. Heterocyclic compound
  2. Alicyclic compound
  3. Aromatic compound
  4. Open-chain compound
Answer: Alicyclic compound
Question 19
The IUPAC name of (CH3)3CH is:
  1. Butane
  2. 2-Methylpropane
  3. 2-Methylbutane
  4. Neopentane
Answer: 2-Methylpropane
Question 20
The correct IUPAC name of the compound (CH3)4C is:
  1. 2,2-Dimethylpropane
  2. Pentane
  3. 2,2-Dimethylbutane
  4. 2-Methylbutane
Answer: 2,2-Dimethylpropane

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