Chemistry Fundamental Principles of Organic Chemistry SZABMU 2024
PMDC Verified Question 7 of 83
Which type of isomerism is shown by fumaric acid and maleic acid?
A
Functional group isomers
B
Optical isomers
C
Geometrical isomers
D
Position isomers
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Geometrical isomers
Concept:

Maleic acid and fumaric acid are classic examples of molecules that have the exact same structural connectivity but different spatial arrangements around a double bond.

Solution:

  • Both acids have the IUPAC name butenedioic acid (\( \text{HOOC-CH=CH-COOH} \)).


  • In maleic acid, the two bulky carboxyl groups (\( \text{-COOH} \)) are locked on the same side of the double bond (cis-isomer).


  • In fumaric acid, the two carboxyl groups are locked on opposite sides of the double bond (trans-isomer).


  • This spatial difference due to restricted rotation is geometrical isomerism.


Why other options are incorrect:

They lack chiral centers, so they are not optical isomers. Their functional groups and positional numbers are identical.

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