Two elements of p-block can form following halides XF$_3$ and YF$_3$. XF$_3$ can act as Lewis acid while YF$_3$ can act as Lewis base. Then hybridization of ‘X’ and ‘Y’ in XF$_3$ and YF$_3$ is respectively.
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In Lewis acid-base theory, Lewis acids tend to have empty orbitals for accepting electron pairs, while Lewis bases have lone pairs available for donation.
Step 1: Understanding the behavior of XF$_3$ and YF$_3$.
- XF$_3$ is a Lewis acid, which means element X must have an incomplete octet or a strong tendency to accept electron pairs. This typically happens when the central atom has a higher oxidation state and can accept electron pairs. This is characteristic of sp$^3$ hybridized species.
- YF$_3$ acts as a Lewis base, which means element Y donates electron pairs. This occurs when element Y has lone pairs of electrons available for donation, and such atoms are typically sp$^3$ hybridized.
Step 2: Analyzing the hybridization of X and Y.
- For XF$_3$, X needs to have an oxidation state of +3, and its hybridization is sp$^3$ to accommodate three bonding pairs with fluorine atoms and leave an empty orbital for accepting electron pairs.
- For YF$_3$, Y needs to have lone pairs to act as a Lewis base. It will also be sp$^3$ hybridized as it needs to accommodate three bonding pairs and retain one lone pair, allowing it to donate electrons.
Step 3: Conclusion.
The hybridization of both X and Y in XF$_3$ and YF$_3$ is sp$^3$. Therefore, the correct answer is (3).
