Step 1: Understanding Hoffmann Bromamide Degradation
The Hoffmann bromamide degradation reaction involves the conversion of an amide (\( \text{CONH}_2 \)) to a primary amine (\( \text{NH}_2 \)) with the loss of one carbon atom.
Step 2: Reaction Mechanism
The reaction takes place in the presence of bromine (\( \text{Br}_2 \)) and sodium hydroxide (\( \text{NaOH} \)), leading to the formation of an amine with one less carbon atom.
Step 3: Identifying the Correct Functional Group
The correct starting compound for this reaction is an amide (\( \text{ArCONH}_2 \)), making option (b) ArCONH\(_2\) the correct choice.
Final Answer: The Hoffmann bromamide degradation reaction is shown by ArCONH\(_2\).