Which is correct statement ?

Options

A. `LiCl` is more soluble in polar solvent (water ) than `NaCl`
B. `K_(a_(2))` of fumaric acid is more than `K_(a_(2))` of maleic acid
C. The `O-O` bond length in `O_(2)[AsF_(4)]` is shorter than `KO_(2)`
D. In `CF_(2)=C=CF_(2)` molecule all the four flourine atoms are in the same plane

Answer

To determine which statement is correct, we need to analyze each statement provided in the question step by step.

### Step 1: Analyze Statement 1
**Statement:** LiCl is more soluble in polar solvent (water) than NaCl.

- **Explanation:** The solubility of ionic compounds in water is influenced by the size of the cations. Lithium (Li) has a smaller ionic radius compared to sodium (Na).
- **Hydration Energy:** The hydration energy is inversely proportional to the size of the cation. Since Li+ has a higher hydration energy due to its smaller size, it interacts more favorably with water molecules, leading to greater solubility.
- **Conclusion:** This statement is **true**.

### Step 2: Analyze Statement 2
**Statement:** Fumaric acid is more acidic than malic acid.

- **Explanation:** Fumaric acid has a structure where the carboxylic groups are further apart, which stabilizes the negative charge when a proton is removed. In contrast, malic acid has a hydroxyl group adjacent to the carboxylic group, which can lead to intramolecular hydrogen bonding and destabilization of the negative charge upon deprotonation.
- **Conclusion:** This statement is **true**.

### Step 3: Analyze Statement 3
**Statement:** The O–O bond length in O2AsF4 is shorter than in KO2.

- **Explanation:** In O2AsF4, the O2 unit is a cation (O2+), while in KO2, the O2 unit is an anion (O2−). The bond order for the cation is higher than that of the anion, which means that the bond length is shorter for the cation due to increased bond strength.
- **Conclusion:** This statement is **true**.

### Step 4: Analyze Statement 4
**Statement:** In CF2=C=CF2, all four fluorine atoms are in the same plane.

- **Explanation:** The structure of CF2=C=CF2 shows that the fluorine atoms are attached to the carbon atoms, which are involved in double bonds. The geometry around the carbon atoms is trigonal planar due to the double bonds, but the spatial arrangement of the fluorine atoms means that they do not all lie in the same plane.
- **Conclusion:** This statement is **false**.

### Final Summary
- Statements 1, 2, and 3 are **true**.
- Statement 4 is **false**.

### Correct Statement
The correct statements are 1, 2, and 3.

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