Which of the bond length order data is INCORRECT

Options

A. `P-Cl gt P-F ` in `PCl_(3)F_(2)`
B. `S-F_("(axial)")gt S-F_("(eq)") ` in `SF_(6)`
C. `S-F_("(axial)") gt S-F_("(eq)") ` in `SF_(4)`
D. `NO_(2)^(-) lt NO_(3)^(-)` (N-O)

Answer

To determine which bond length order data is incorrect, we will analyze each statement provided in the question step by step.

### Step-by-Step Solution:

1. **Statement 1: PCl bond length is greater than PF bond length.**
- **Analysis:** In PCl3F2, chlorine (Cl) is less electronegative than fluorine (F). Therefore, the P-Cl bond will be longer than the P-F bond due to the lower electronegativity of Cl leading to less effective overlap and a longer bond length. This statement is **correct**.

2. **Statement 2: SF axial bond length is greater than SF equatorial bond length in SF6.**
- **Analysis:** SF6 has an octahedral geometry where all six S-F bonds are equivalent due to symmetrical arrangement. There are no axial or equatorial bonds in SF6, as all bonds are equal. Therefore, this statement is **incorrect**.

3. **Statement 3: SF axial bond length is greater than SF equatorial bond length in SF4.**
- **Analysis:** In SF4, which has a seesaw shape due to the presence of a lone pair, the axial S-F bonds experience more repulsion than the equatorial S-F bonds. Therefore, the axial bonds are longer than the equatorial bonds. This statement is **correct**.

4. **Statement 4: The bond length of NO3- is greater than the bond length of NO2-.**
- **Analysis:** In NO2-, the bond order is 1.5 (due to resonance), while in NO3-, the bond order is 1.33. Since bond length is inversely proportional to bond order, NO3- will have a longer bond length than NO2-. This statement is **correct**.

### Conclusion:
The incorrect statement is **Statement 2: SF axial bond length is greater than SF equatorial bond length in SF6**.