Choose CORRECT order of bond length

Options

A. S-S bond length : `S_(2)O_(4)^(2-) gt S_(2)O_(6)^(2-)`
B. O-O bond length : `H_(2)O_(2) gt O_(2)F_(2)`
C. N-N bond length : `N_(2)O_(3) gt N_(2)O_(4)`
D. All are correct

Answer

To determine the correct order of bond lengths for the given compounds, we will analyze each pair of compounds based on their structures and the presence of lone pairs of electrons, which can affect bond lengths due to repulsion.

### Step-by-Step Solution:

1. **Analyzing S2O4²⁻ and S2O6²⁻:**
- **Structure of S2O4²⁻:** The structure has sulfur (S) atoms bonded to four oxygen (O) atoms. Each sulfur has one lone pair of electrons. The presence of lone pairs leads to increased repulsion between the lone pairs and the bonding pairs, which results in longer S-S bond lengths.
- **Structure of S2O6²⁻:** In this structure, there are three oxygen atoms bonded to each sulfur atom, and there are no lone pairs on the sulfur atoms. The absence of lone pairs means there is less repulsion, leading to shorter S-S bond lengths compared to S2O4²⁻.
- **Conclusion:** The bond length in S2O4²⁻ is greater than in S2O6²⁻.

2. **Analyzing H2O2 and O2F2:**
- **Structure of H2O2:** This molecule has an open book-like structure with two oxygen atoms bonded to each other and to hydrogen atoms. The electron density is relatively high due to the presence of hydrogen.
- **Structure of O2F2:** In this molecule, the oxygen atoms are bonded to fluorine atoms. Fluorine is highly electronegative and pulls electron density away from the oxygen atoms, leading to less electron density around the O-O bond. This results in increased repulsion between the bonding pairs of electrons.
- **Conclusion:** The bond length in H2O2 is greater than in O2F2.

3. **Analyzing N2O3 and N2O4:**
- **Structure of N2O3:** This compound has nitrogen atoms bonded to oxygen atoms with one nitrogen having a lone pair. The lone pair leads to increased repulsion, which increases the N-N bond length.
- **Structure of N2O4:** In this structure, there are no lone pairs on the nitrogen atoms, resulting in less repulsion between the bonding pairs.
- **Conclusion:** The bond length in N2O3 is greater than in N2O4.

### Final Conclusion:
Based on the analysis above, the correct order of bond lengths is:
- S2O4²⁻ > S2O6²⁻
- H2O2 > O2F2
- N2O3 > N2O4

Thus, all pairs show that the first compound has a greater bond length than the second compound.