Arrange given diabasic acids in decreasing order of acidic strength 1. Oxalic acid 2. Adipic acid 3. Malonic acid 4. Succinic acid

Options

A. 1,3,4,2
B. 1,4,3,2
C. 3,4,2,1
D. 2,3,1,4

Answer

To determine the decreasing order of acidic strength for the given dibasic acids (Oxalic acid, Adipic acid, Malonic acid, and Succinic acid), we need to analyze the structure and the effects of substituents on their acidity.

### Step-by-Step Solution:

1. **Identify the Structure of Each Acid:**
- **Oxalic Acid (C2H2O4)**: It has two carboxylic acid groups (-COOH) and no alkyl groups.
- **Malonic Acid (C3H4O4)**: It has two carboxylic acid groups and one methylene (-CH2-) group.
- **Succinic Acid (C4H6O4)**: It has two carboxylic acid groups and two methylene (-CH2-) groups.
- **Adipic Acid (C6H10O4)**: It has two carboxylic acid groups and four methylene (-CH2-) groups.

2. **Understanding Acidic Strength:**
- The acidic strength of a compound is influenced by the stability of its conjugate base after losing a proton (H+).
- Electron-withdrawing groups increase acidity by stabilizing the negative charge on the conjugate base, while electron-donating groups (like alkyl groups) decrease acidity by destabilizing the negative charge.

3. **Analyze Each Acid:**
- **Oxalic Acid**: It has no electron-donating alkyl groups, making it the strongest acid among the four.
- **Malonic Acid**: It has one -CH2- group, which is a weak electron-donating group, thus it is less acidic than oxalic acid.
- **Succinic Acid**: It has two -CH2- groups, further decreasing its acidity compared to malonic acid.
- **Adipic Acid**: It has four -CH2- groups, making it the least acidic due to the maximum electron-donating effect.

4. **Order of Acidity:**
- Based on the analysis, the decreasing order of acidic strength is:
1. **Oxalic Acid**
2. **Malonic Acid**
3. **Succinic Acid**
4. **Adipic Acid**

### Final Answer:
**Decreasing order of acidic strength:**
1. Oxalic Acid
2. Malonic Acid
3. Succinic Acid
4. Adipic Acid