Organic Chemistry Basics Quiz

Grade 11 · Science · Quiz

10 questions on carbon chemistry, hydrocarbon classes, functional groups, isomers, and reaction types.

Questions

1. Which hydrocarbon class contains only single carbon-carbon bonds?

   1. Alkene
   2. Alkyne
   3. Alkane
   4. Aromatic
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   Answer: Alkane

   Alkanes are saturated hydrocarbons with only C-C single bonds; formula CₙH₂ₙ₊₂.

2. Ethanol (CH₃CH₂OH) belongs to which functional group class?

   1. Ester
   2. Alcohol
   3. Aldehyde
   4. Amine
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   Answer: Alcohol

   The −OH (hydroxyl) group defines alcohols. Ethanol is the most common alcohol.

3. Which hydrocarbon type contains a triple bond?

   1. Alkane
   2. Alkene
   3. Alkyne
   4. Aromatic
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   Answer: Alkyne

   Alkynes contain at least one C≡C triple bond; general formula CₙH₂ₙ₋₂.

4. The fruity aromas of many fruits result from which functional group?

   1. Amines
   2. Esters
   3. Carboxylic acids
   4. Aldehydes
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   Answer: Esters

   Esters (−COO−) produce characteristic fruity scents. Isoamyl acetate gives bananas their smell.

5. Butane (C₄H₁₀) and isobutane both have the formula C₄H₁₀ but different structures. They are:

   1. Isotopes
   2. Structural isomers
   3. Geometric isomers
   4. Identical compounds
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   Answer: Structural isomers

   Structural isomers have the same molecular formula but different connectivity of atoms. Butane is a straight chain; isobutane is branched.

6. Which reaction type removes atoms to create a new double bond?

   1. Addition
   2. Substitution
   3. Elimination
   4. Condensation
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   Answer: Elimination

   Elimination reactions remove atoms from adjacent carbons, forming a new pi (double) bond. E.g., alcohol → alkene + water.

7. Aromatic compounds like benzene are characterized by:

   1. Only single bonds
   2. A triple bond in the ring
   3. Delocalized pi electrons in a ring
   4. High reactivity with water
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   Answer: Delocalized pi electrons in a ring

   Benzene's six pi electrons are delocalized around the ring, giving it exceptional stability — the hallmark of aromaticity.

8. Amino acids link together by releasing water. This is a:

   1. Addition reaction
   2. Elimination reaction
   3. Condensation reaction
   4. Substitution reaction
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   Answer: Condensation reaction

   Condensation reactions join two molecules with the release of a small molecule (water). This is how peptide bonds form.

9. Which functional group makes carboxylic acids weakly acidic?

   1. −OH alone
   2. −NH₂
   3. −COOH (both C=O and −OH)
   4. C=C double bond
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   Answer: −COOH (both C=O and −OH)

   The carboxyl group's C=O withdraws electron density, making the −OH proton more acidic and easily donated.

10. How many valence electrons does carbon have?

    1. 2
    2. 3
    3. 4
    4. 6
    Show answer

    Answer: 4

    Carbon is in Group 14 and has 4 valence electrons, enabling it to form 4 covalent bonds and create enormous structural diversity.

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