Which organic compound can reduces Tollen's reagent ?

Options

A. Oxalic acid
B. Citric acid
C. Acetic acid
D. Formic acid

Answer

To determine which organic compound can reduce Tollen's reagent, we need to identify the presence of an aldehyde functional group in the given compounds. Tollen's reagent is specifically used to test for aldehydes, which can be oxidized to carboxylic acids while reducing the silver ion in the reagent to metallic silver, resulting in a silver mirror.

### Step-by-Step Solution:

1. **Understanding Tollen's Reagent**:
Tollen's reagent is a solution of silver nitrate (AgNO3) in ammonia (NH3). It is used to test for the presence of aldehydes. Aldehydes can reduce Tollen's reagent, resulting in the formation of a silver mirror.

**Hint**: Remember that Tollen's reagent is specifically for detecting aldehydes.

2. **Identifying the Functional Groups**:
We need to analyze the given compounds to check for the presence of the aldehyde functional group (-CHO).

- **Option 1: Oxalic Acid (HOOC-COOH)**:
- Structure: Contains two carboxylic acid groups (COOH) and no aldehyde group.
- Conclusion: Does not reduce Tollen's reagent.

**Hint**: Look for the -CHO group in the structure.

- **Option 2: Citric Acid (C6H8O7)**:
- Structure: Contains three carboxylic acid groups and one hydroxyl group (OH) but no aldehyde group.
- Conclusion: Does not reduce Tollen's reagent.

**Hint**: Check if there are any -CHO groups in the structure.

- **Option 3: Acetic Acid (CH3COOH)**:
- Structure: Contains one carboxylic acid group and no aldehyde group.
- Conclusion: Does not reduce Tollen's reagent.

**Hint**: Identify if the compound has an aldehyde functional group.

- **Option 4: Formic Acid (HCOOH)**:
- Structure: Contains one carboxylic acid group (COOH) and one aldehyde group (CHO).
- Conclusion: Can reduce Tollen's reagent because it contains the aldehyde group.

**Hint**: Look for compounds that have both carboxylic acid and aldehyde functionalities.

3. **Final Conclusion**:
The only compound that can reduce Tollen's reagent is **Formic Acid (HCOOH)**, as it contains the aldehyde functional group.

### Answer:
**Formic Acid (HCOOH)** is the organic compound that can reduce Tollen's reagent.