a. How many isomers are possible for the compound with the molecular

formula C 4 H 8 ? Draw the electron dot structure of branched chain isomer.

b. How will you prove that C 4 H 8 and C 5 H 10 are homologues?


a. Four

Question 9 Choice 1.jpg

4 isomers are Possible with C4H8 as shown below


Isomers are

Organic Compounds having similar molecular formula but different structures

It is possible only in hydrocarbons having 4 or more carbon atoms

1-butene, cis-2-butene, trans-2-butene, and isobutylene.

isomers geometric.png


Branched Chain Isomer

In this case,3 carbon atom are put in straight chain

Fourth Carbon atom is put in side as shown below


b. C 4 H 8 and C 5 H 10 are homologues 

as they differ in

● “- CH 2 -”

● differ in 14u molecular mass

● Same functional group

● Same general formula 

(Any two reasons)


Homologues are group of chemical compounds which have similar structure and similar chemical properties and successive compounds differ by CH2


Example of Homologues Series of Alkenes

Ethene C2H4

Propene C3H6

Butene C4H8

Pentene C5H10

Hexene C6H12


It can be seen that

Difference between C4H8 and C5H10 is CH2

Also these 2 share similar structure and chemical properties (both are alkenes)

Hence these are homologues

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CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo