Question

Xenon hexafluoride on partial hydrolysis gives 'X' and HF. The shape of 'X' is

• A. Pyramidal
• B. Tetrahedral
• C. Square pyramidal
• D. Linear

Hint:

Complete hydrolysis of \( \text{XeF}_6 \) gives \( \text{XeO}_3 \) (Pyramidal). Partial gives \( \text{XeOF}_4 \) (Square Pyramidal) or \( \text{XeO}_2\text{F}_2 \) (See-Saw).

Answer 1

The Correct Option is C

Step 1: Hydrolysis Reaction:

Partial hydrolysis of \( \text{XeF}_6 \) yields Xenon Oxytetrafluoride (\( \text{XeOF}_4 \)). \[ \text{XeF}_6 + \text{H}_2\text{O} \to \text{XeOF}_4 + 2\text{HF} \] So, Compound X is \( \text{XeOF}_4 \).
Step 2: VSEPR Theory Application for \( \text{XeOF}_4 \):

- Central Atom: Xe (Group 18, 8 valence electrons). - Bonding: - 4 bonds to F (monovalent) $\to$ 4 electrons used. - 1 double bond to O (divalent) $\to$ 2 electrons used. - Total electrons involved in bonding = 6. - Lone Pairs: \( 8 - 6 = 2 \) electrons remaining, which form 1 Lone Pair. - Steric Number: Number of sigma bonds + Lone pairs = \( 4 (\text{Xe-F}) + 1 (\text{Xe=O}) + 1 (\text{LP}) = 6 \). - Hybridization: \( sp^3d^2 \) (Octahedral geometry).
Step 3: Determining Shape:

In an octahedral geometry with 1 lone pair, the lone pair occupies an axial position (to minimize repulsion with the double bond, usually placed trans to the Oxygen or simply considering symmetry). The arrangement of atoms forms a square base (4 Fluorines) with the Oxygen at the apex. This shape is called Square Pyramidal.
Step 4: Final Answer:

The shape is Square pyramidal.