$word_{count}$: 200

2,4-DNP test: Yellow/orange/red precipitate — detects ALL C=O (aldehydes AND ketones). Tollens' test (Ag+/NH3): Silver mirror — detects ALL aldehydes (aliphatic and aromatic); ketones negative. Fehling's test (Cu2+/tartrate): Red Cu2O precipitate — detects ALIPHATIC aldehydes only; aromatic aldehydes and all ketones negative. Schiff's test (fuchsin-SO2): Pink color — aldehydes only; ketones negative or very slow. Iodoform test $\frac{I2}{NaOH}$: Yellow CHI3 precipitate — detects: (1) CH3CHO, (2) all RCOCH3, (3) C2H5OH (oxidized to CH3CHO), (4) RCHOHCH3 (oxidized to RCOCH3). NaHSO3 addition: White crystalline precipitate — all aldehydes + methyl ketones + small cyclic ketones. Benedict's test: Similar to Fehling's — detects reducing sugars (free or potential aldehyde group). Decision tree: Positive 2,4-DNP + negative Tollens' = ketone. Positive 2,4-DNP + positive Tollens' + negative Fehling's = aromatic aldehyde. Positive all three = aliphatic aldehyde.