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 arrange the given dibasic acids (Oxalic acid, Adipic acid, Malonic acid, and Succinic acid) in decreasing order of acidic strength, we need to analyze the structure of each acid and the factors that influence their acidity.

### Step-by-Step Solution:

1. **Identify the Structures:**
- **Oxalic Acid (C2H2O4)**: It has two carboxylic acid groups (-COOH) directly attached to each other.
- **Malonic Acid (C3H4O4)**: It has two carboxylic acid groups with a -CH2- group in between.
- **Succinic Acid (C4H6O4)**: It has two carboxylic acid groups with two -CH2- groups in between.
- **Adipic Acid (C6H10O4)**: It has two carboxylic acid groups with four -CH2- groups in between.

2. **Consider Electron-Withdrawing and Electron-Donating Effects:**
- Acidity is influenced by the stability of the anion formed after deprotonation. Electron-withdrawing groups stabilize the negative charge, enhancing acidity, while electron-donating groups decrease acidity.
- In this case, the presence of -CH2- groups (which are electron-donating) in Malonic, Succinic, and Adipic acids reduces their acidity compared to Oxalic acid, which has no such groups.

3. **Analyze the Acidity:**
- **Oxalic Acid**: The two -COOH groups are directly attached, allowing for effective stabilization of the negative charge on the anion formed after losing a proton. Hence, it is the most acidic.
- **Malonic Acid**: The presence of one -CH2- group reduces the acidity compared to Oxalic acid but is still more acidic than Succinic and Adipic acids.
- **Succinic Acid**: With two -CH2- groups, it is less acidic than Malonic acid.
- **Adipic Acid**: With four -CH2- groups, it has the most electron-donating effect, making it the least acidic among the four.

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

### Final Answer:
The decreasing order of acidic strength is:
**Oxalic Acid > Malonic Acid > Succinic Acid > Adipic Acid**