Reaction Mechanism

Step 1: Target Compound
-chloroacetic acid ( ) is a carboxylic acid where a chlorine atom is substituted at the alpha-carbon.
Step 2: Identification of HVZ Reaction
The Hell-Volhard-Zelinsky (HVZ) reaction involves the halogenation of carboxylic acids at the -position using or in the presence of red phosphorus.
Step 3: Reaction Mechanism
.
Step 4: Conclusion
Therefore, the HVZ reaction is the suitable method.
Final Answer: (A)

Step 1: Understanding the Concept:
Azo coupling is an electrophilic aromatic substitution reaction. Reactivity depends on electron density of the ring.

Step 2: Detailed Explanation:
Electron-donating groups increase reactivity, while electron-withdrawing groups decrease it.
Thus, the increasing order of reactivity is: IV
Step 3: Final Answer:
IV - II - III - I

Step 1: Understanding the Concept:
Electron-withdrawing groups (NO ) influence nucleophilic substitution reactions.

Step 2: Detailed Explanation:
In this case, the meta-nitro group affects the reactivity differently compared to ortho and para positions due to reduced resonance interaction with the leaving group.

Step 3: Final Answer:
m-nitrophenyl chloride