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CHEMISTRY CBSE CLASS X

Homologous Series

3. Aldehyde  Group :
   

   It consists of 1 carbon, 1 hydrogen and 1 oxygen atom joined together.

   General formula  --- C_nC_2nO

   Methanal  -  HCHO ---  formaldehyde
   Ethanal     -  CH₃CHO ---- acetaldehyde
   Propanal – CH₃CH₂CHO  ---  propionaldehyde
   Butanal  -  CH₃CH₂CH₂CHO

4. Ketone  Group :
   

   It consists of 1 carbon and 1 oxygen atom. A ketone group must contain at least 3 carbon atoms.
   General formula  -- C_nC_2nO
   Propanone  -  CH₃COCH₃ ----  acetone  ( simplest ketone)
   Butanone    -  CH₃COCH₂CH₃
   Pentanone -  CH₃COCH₂CH₂CH₃

5. Carboxylic Acid Group  :
   

   It is present in Methanoic acid  ( formic acid) - HCOOH  
   Ethanoic Acid  ( acetic acid) - CH₃−COOH 
   Propionic Acid - C₂H₅COOH or CH₃CH₂COOH
   They are also called Organic acids and contain carbon , hydrogen and oxygen.

6. Alkene  Group  :
   

   It is a Carbon – carbon double bond.
   Ethene   -  CH₂ = CH₂  
   Propene -  CH₃− CH = CH₂

7. Alkyne Group  : −C≡C−
   

   Ethyne  -  CH≡CH
   Propyne  - CH₃−C≡CH

Submitted By Mrs. Kritika Bhola
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