Question

The molecule that has ONLY one lone pair of electrons on xenon is _ _ _.

• A. XeF$_2$
• B. XeF$_4$
• C. XeO$_2$F$_2$
• D. XeO$_3$F$_2$

Hint:

Use steric number = bond pairs + lone pairs to quickly determine number of lone pairs in noble gas compounds

Answer 1

The Correct Option is C

Step 1: Count total valence electrons of Xe.
Xenon has 8 valence electronsWe determine lone pairs using steric number (bond pairs + lone pairs)

Step 2: Analyze each option.
\[ \text{XeF}_2 \] Total bonds = 2 → steric number = 5 → lone pairs = 3
\[ \text{XeF}_4 \] Total bonds = 4 → steric number = 6 → lone pairs = 2
\[ \text{XeO}_2\text{F}_2 \] Total bonds = 4 (2 Xe=O + 2 Xe–F) → steric number = 5 → lone pairs = 1
\[ \text{XeO}_3\text{F}_2 \] Total bonds = 5 → steric number = 6 → lone pairs = 1

Step 3: Check correct structure.
In XeO$_2$F$_2$, xenon has one lone pair and trigonal bipyramidal geometry

Step 4: Conclusion.
\[ \boxed{\text{XeO}_2\text{F}_2} \]