Which of the followingg statement(s) is/are false?

Options

A. In `[PtCl_(2)(NH_(3))_(4)]^(2+)` complex ion, the cis-form is optically active, while trans-form is optically inactive
B. In `[Fe(C_(2)O_(4))_(3)]^(3-)`, geometrical isomerism does not exist, while optical isomerism exist
C. In `[Mabcd]^(n+-)` tetrahedral complexes, optical isomerism cannot be observed
D. In `[Mabcd]^(n+-)` square planar complex, optical isomerism can be observed

Explanation

To determine which statements are false regarding coordination compounds, we will analyze each statement step by step.

### Step 1: Analyze the First Statement
**Statement:** In [PtCl2(NH3)4]²⁺, the cis form is optically active while the trans form is optically inactive.

**Analysis:**
- The complex [PtCl2(NH3)4]²⁺ has a square planar geometry.
- In the trans form, the two Cl ligands are opposite each other, creating a plane of symmetry. This means it is optically inactive.
- In the cis form, the two Cl ligands are adjacent, but there is still a plane of symmetry due to the arrangement of the ligands. Therefore, it is also optically inactive.

**Conclusion:** The first statement is false.

### Step 2: Analyze the Second Statement
**Statement:** In the complex [Fe(C2O4)3]³⁻, geometrical isomers do not exist while optical isomerism does exist.

**Analysis:**
- The complex [Fe(C2O4)3]³⁻ has a coordination number of 6 and consists of bidentate ligands (oxalate).
- Since there is no symmetry in the arrangement of the oxalate ligands, only optical isomers exist, and geometrical isomers do not.

**Conclusion:** The second statement is true.

### Step 3: Analyze the Third Statement
**Statement:** In MA2BC tetrahedral complexes, optical isomerism can't be observed.

**Analysis:**
- Tetrahedral complexes can have different arrangements of ligands. If the ligands are arranged such that there is no plane of symmetry, optical isomerism can occur.
- Therefore, it is possible for optical isomerism to be observed in tetrahedral complexes.

**Conclusion:** The third statement is false.

### Step 4: Analyze the Fourth Statement
**Statement:** In MA2BC square planar complexes, optical isomerism can be observed.

**Analysis:**
- Square planar complexes often have a plane of symmetry due to their arrangement. If there is a plane of symmetry, optical isomerism cannot occur.
- Therefore, square planar complexes typically do not exhibit optical isomerism.

**Conclusion:** The fourth statement is false.

### Final Conclusion
The false statements are:
1. The first statement is false.
2. The third statement is false.
3. The fourth statement is false.

Thus, the answer is that statements 1, 3, and 4 are false.