Misconception 1

Wrong: "All alcohols give positive iodoform test." Correct: Only ethanol (CH3CH2OH) and isopropanol (CH3CHOHCH3) among simple alcohols give positive iodoform. They must be oxidizable to a compound with the CH3CO- group. Methanol, propan-1-ol, propan-2-ol (nope — propan-2-ol does give iodoform! it oxidizes to acetone). Clarification: CH3CHOH-R (secondary alcohol with CH3 on the OH carbon) → oxidizes to CH3CO-R → iodoform. Only this pattern is positive.

Misconception 2

Wrong: "Benzaldehyde gives positive Fehling's test because it's an aldehyde." Correct (for NEET context): Benzaldehyde gives positive Tollens' but is debated for Fehling's. For NEET: use Tollens' to identify benzaldehyde. Aromatic aldehydes may give borderline Fehling's results.

Misconception 3

Wrong: "Concentrated NaOH always causes Cannizzaro; dilute NaOH always causes aldol." Correct: The concentration of NaOH matters for the mechanism, but the PRIMARY deciding factor is ALWAYS alpha-H presence. Even if conc. NaOH is used with CH3CHO, aldol (not Cannizzaro) occurs because CH3CHO has alpha-H.

Misconception 4

Wrong: "Nucleophilic addition to C=C alkenes and C=O carbonyls work the same way." Correct: Alkenes undergo ELECTROPHILIC addition (pi electrons attack electrophile). Carbonyl compounds undergo NUCLEOPHILIC addition (nucleophile attacks electrophilic $C^{delta+}$). The mechanisms are different.

Misconception 5

Wrong: "Clemmensen reduction gives alcohol as a product." Correct: Clemmensen (Zn-Hg/conc. HCl) gives the methylene compound (CH2) — complete deoxygenation. There is no alcohol intermediate. NaBH4/LiAlH4 gives alcohol.

Misconception 6

Wrong: "Both NaBH4 and LiAlH4 have identical scope and selectivity." Correct: NaBH4 is selective for aldehydes and ketones (does not reduce esters, carboxylic acids, or amides). LiAlH4 reduces all carbonyl-containing compounds including esters, acids, and amides. For NEET, both give alcohol from aldehydes/ketones.