Question

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. Tollen reagent is used in detection of unsaturation
• D. ${NaHSO_3}$ is used in detection of carbonyl compound

Answer 1

The Correct Option is C

To determine which statement is incorrect, let's analyze each option with respect to their chemical properties and uses:

1. ${FeCl_3}$ is used in detection of phenol:
   • This statement is correct. ${FeCl_3}$, also known as ferric chloride, is used in the ferric chloride test to detect phenol. Phenol forms a complex with ${FeCl_3}$ resulting in a violet coloration.
2. Fehling solution is used in detection of glucose:
   • This statement is correct. Fehling's solution is commonly used to detect reducing sugars like glucose. When glucose is present, the Cu²⁺ ions in Fehling's solution get reduced to Cu₂O, which forms a red precipitate.
3. Tollen reagent is used in detection of unsaturation:
   • This statement is incorrect. Tollen's reagent is actually used to detect aldehydes, not unsaturation. It is used in the silver mirror test, where aldehydes reduce Tollen's reagent containing silver ions to metallic silver.
4. ${NaHSO_3}$ is used in detection of carbonyl compound:
   • This statement is correct. ${NaHSO_3}$, or sodium bisulfite, is used to detect carbonyl compounds. It forms a bisulfite addition complex with aldehydes and some ketones.

Based on the analysis, the incorrect statement is: "Tollen reagent is used in detection of unsaturation." Tollen reagent is used for detecting aldehydes.