CBSE Class 12 · 2008 · All India · Aldehydes Ketones and Carboxylic AcidsShort Answer

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State chemical tests to distinguish between the following pairs of compounds:
i) propanal and propanone
ii) phenol and benzoic acid

Answer: (i) Tollens'/Fehling — positive for propanal only. (ii) NaHCO₃ effervescence for benzoic acid; FeCl₃ violet for phenol.

Solution

(i) Propanal gives the silver mirror (Tollens') and red CuO (Fehling); propanone gives neither.
(ii) Benzoic acid: CO with NaHCO. Phenol: violet with neutral FeCl (no CO with bicarbonate).

CBSE Class 12 Board · 2008 · All India · Subjective

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