Based on NEET previous year question analysis (2017-2024), the following concepts from OC-05 are most frequently tested:

1. PCC vs $KMnO_{4}$ (Most Frequent — appears almost every year): The distinction between PCC (stops at aldehyde) and $KMnO_{4}$/$K_{2}Cr_{2}O_{7}$ (goes to carboxylic acid) is the single highest-yield concept in this chapter. Questions typically present a primary alcohol and ask for the product with a specific reagent.

• 1-Propanol (SMILES:CCCO) + PCC → Propanal (SMILES:CCC=O) ← NEET ANSWER
• 1-Propanol + $KMnO_{4}$ → Propanoic acid (SMILES:CCC(=O)O)

2. Phenol Acidity and Substituent Effects (Very Frequent): Questions present substituted phenols and ask students to arrange them in order of acidity or identify the most/least acidic.

• Order: p-$NO_{2}$ phenol > p-Cl phenol > phenol > p-$CH_{3}$ phenol
• Reasoning always based on EWG stabilizing phenoxide (more acidic) or EDG destabilizing it (less acidic)

3. Named Reactions of Phenol (Frequent): Questions identify products of Kolbe or Reimer-Tiemann reactions, sometimes asking for the intermediate.

• Kolbe → salicylic acid (ortho -COOH)
• Reimer-Tiemann → salicylaldehyde (ortho -CHO) via :$CCl_{2}$

4. Williamson Synthesis Conditions (Frequent): Questions identify the correct reagent combination or explain why a combination fails.

• Correct: primary alkyl halide + alkoxide → ether
• Incorrect (trap): 3° alkyl halide → gives alkene (E2), not ether

5. Phenol Bromination (Moderate Frequency): Questions test whether students know that phenol requires no Lewis acid catalyst for bromination and gives the 2,4,6-tribromo product.

Trap Pattern to Avoid: A question may present "2° alcohol + $KMnO_{4}$ → ?" hoping students say carboxylic acid. The correct answer is ketone — $KMnO_{4}$ cannot oxidize a ketone further under normal conditions.