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Which of the following is incorrect : -
A
$FeCl_3$ is used in detection of phenol
B
Fehling solution is used in detection of glucose
C
Tollens reagent is used in detection of unsaturation
D
$NaHSO_3$ is used in detection of carbonyl compound
Detailed Solution
Neutral $FeCl_3$ gives a violet colour with phenols; correct.
Fehling's solution is reduced by glucose (a reducing sugar) to a red precipitate of $Cu_2O$; correct.
Sodium bisulphite forms crystalline addition products with aldehydes and many ketones; correct.
Tollens' reagent (ammoniacal silver nitrate) is used to detect aldehydes (silver mirror test), not unsaturation. Unsaturation (C=C) is detected with bromine water or Baeyer's reagent (cold dilute alkaline $KMnO_4$).
So the incorrect statement is that Tollens' reagent is used in detection of unsaturation.
Fehling's solution is reduced by glucose (a reducing sugar) to a red precipitate of $Cu_2O$; correct.
Sodium bisulphite forms crystalline addition products with aldehydes and many ketones; correct.
Tollens' reagent (ammoniacal silver nitrate) is used to detect aldehydes (silver mirror test), not unsaturation. Unsaturation (C=C) is detected with bromine water or Baeyer's reagent (cold dilute alkaline $KMnO_4$).
So the incorrect statement is that Tollens' reagent is used in detection of unsaturation.