Which of the following is incorrect?

Options

A. `FeCl_(3)` is used is detection of phenol
B. Fehling solution is used in detection of glucose
C. Tollen's reagent is used in detection of unsaturation
D. `NaHSO_(3)` is used in detection of carbonyl compound

Answer

To determine which statement is incorrect, let's analyze each statement one by one.

### Step 1: Analyze the First Statement
**Statement 1:** "FACL-3 is used in the detection of phenol."

- **Analysis:** This statement is true. Ferric chloride (FeCl3) is indeed used to detect phenols. When phenol reacts with FeCl3, it forms a violet complex, confirming the presence of phenol.

### Step 2: Analyze the Second Statement
**Statement 2:** "Phalanx solution is used in the detection of glucose."

- **Analysis:** This statement is also true. The Fehling's solution (often confused with "phalanx") is used to detect reducing sugars like glucose. The aldehyde group in glucose reacts with Fehling's solution, resulting in the formation of a red precipitate of Cu2O.

### Step 3: Analyze the Third Statement
**Statement 3:** "Tolerance reagent is used in the detection of unsaturation."

- **Analysis:** This statement is false. The Tollen's reagent (ammoniacal silver nitrate) is used to detect aldehydes, not unsaturation. When an aldehyde is present, it reduces the Tollen's reagent to form a silver mirror. Therefore, this statement is incorrect.

### Step 4: Analyze the Fourth Statement
**Statement 4:** "NaHCO3 is used in the detection of carbonyl compounds."

- **Analysis:** This statement is true. Sodium bicarbonate (NaHCO3) can react with carbonyl compounds, particularly aldehydes and ketones, to form a carboxylic acid and release carbon dioxide gas. This reaction indicates the presence of carbonyl compounds.

### Conclusion
Based on the analysis, the incorrect statement is:
**Statement 3:** "Tolerance reagent is used in the detection of unsaturation."