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Homologous Series | Class 9 | Notes, Video, MCQs | SM-Educate

Homologous Series | Class 9 | Notes, Video, MCQs | SM-Educate
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CS-991 · Module O-93

Homologous Series

Class IX · Organic Basics
▶Homologous Series in Organic Chemistry▶General Formula of Alkanes, Alkenes and Alkynes
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📑 What is a Homologous Series?

A homologous series is a group of organic compounds that have the same general formula and similar chemical properties. Each member differs by a CH₂ group.

✅ Characteristics

  • Same general formula
  • Similar chemical properties
  • Gradual change in physical properties
  • Each member differs by a CH₂ group

📊 General Formulas & Examples

NameFormulaType
MethaneCH₄Alkane
EthaneC₂H₆Alkane
PropaneC₃H₈Alkane
ButaneC₄H₁₀Alkane
EtheneC₂H₄Alkene
PropeneC₃H₆Alkene
EthyneC₂H₂Alkyne
PropyneC₃H₄Alkyne

📝 Practice MCQs

Q1: A homologous series is a group of compounds having:
a) Different functional groups b) Similar chemical properties c) Different molecular structures only d) Different elements
Show Answer
✅ b) Similar chemical properties
Q2: Successive members of a homologous series differ by:
a) CH₄ b) CH₂ c) C₂H₂ d) H₂
Show Answer
✅ b) CH₂
Q3: Methane, Ethane and Propane belong to:
a) Alkenes b) Alkynes c) Alkanes d) Alcohols
Show Answer
✅ c) Alkanes
Q4: Members of a homologous series have:
a) Same functional group b) Same molecular formula c) Same number of carbon atoms d) Same physical state only
Show Answer
✅ a) Same functional group
Q5: Ethane differs from methane by:
a) CH₂ b) CH₄ c) H₂ d) C₂H₂
Show Answer
✅ a) CH₂
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