Select the correct statement:

Options

A. Chelation effect is maximum for five and six membered rings
B. Greater the charge on the central metal cation, greater the value of `Delta(CFSE)`
C. In complex ion `[CoF_(6)]^(3-),F^(-)` is a weak field ligand, so that `Delta_(oct) lt P`(Pairng energy) and it is low spin complex
D. `[CoCl_(2)(NH_(3))_(2)(en)]^(o+)` complex ion will have four different isomers

Explanation

To solve the question, we need to analyze each statement provided in the video transcript and determine which ones are correct.

### Step-by-Step Solution:

1. **Statement 1: Chelation effect is maximum for 5 and 6 membered rings.**
- **Analysis:** The chelation effect refers to the increased stability of a complex due to the formation of rings involving the metal ion and the ligands. It is well-established that 5 and 6 membered rings provide optimal stability due to favorable geometric and electronic factors. Therefore, this statement is **true**.

2. **Statement 2: Greater the charge on the central metal cation, greater is the value of crystal field stabilization energy (CFSE).**
- **Analysis:** The crystal field stabilization energy increases with the positive charge on the central metal ion because a higher charge leads to a stronger attraction between the metal ion and the ligands. This results in greater splitting of the d-orbitals and thus higher CFSE. Therefore, this statement is also **true**.

3. **Statement 3: In complex ions COF6^3-, fluoro is a weak field ligand, so that splitting energy of octahedral is less than pairing energy and it is a low spin type complex.**
- **Analysis:** Fluoride (F-) is indeed a weak field ligand, which means that it does not cause significant splitting of the d-orbitals. In this case, the pairing energy is greater than the splitting energy, leading to a high spin complex where electrons remain unpaired. Therefore, this statement is **false**.

4. **Statement 4: COCl2(NH3)(EN) complex will have four different isomers.**
- **Analysis:** The complex COCl2(NH3)(EN) can exhibit geometric isomerism (cis and trans) and optical isomerism due to the presence of the bidentate ligand (EN). This results in a total of four isomers: two optical isomers (cis) and two geometrical isomers (trans). Therefore, this statement is **true**.

### Conclusion:
The correct statements are:
- Statement 1: True
- Statement 2: True
- Statement 3: False
- Statement 4: True

Thus, the correct options are **A, B, and D**.