Isomerism – Answers to Practice Questions

1.  How many different alkanes with C6H14 molecular formula can you make? Draw their skeletal formulae and name them.


isomers of hexane


2.  What is the shortest chain-length alkane to have structural isomers ?       

butane – which has the isomer methylpropane


3.  Draw all the isomers of C4H8 you can think of. Which can have cis-trans isomers ?


isomers of C4H8

4. Draw skeletal formulae of cis-hex-3-ene and trans-hex-3-ene

hex-3-ene isomers

5.  Which of the following molecules has chiral centers, and where are they?

CH3CH2CH2CH­2CH­2OH     no chiral centre

CH3CH2C*H(NH2)CH3          chiral centre shown by *

CH3CHClCH3                             no chiral centre

CH3C*H(OH)Br                     chiral centre shown by *

CH3CH(CH3)C*H(OH)C*H(CH3)CH2CH3      two chiral centres each shown by *

6.  Draw the optical isomers of serine,  H2NCH(CH2OH)COOH

serine opical isomers