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Q.
Boron is unable to form $BF_{6}^{3-}$ ions due to
The p-Block Elements
Solution:
Boron does not have d orbitals. Because of this, it is not possible for the element to expand on its octet. This causes the maximum covalence of boron to be restricted to 4 .Beyond this value, boron will become unstable and thus, cannot form $BF _{6}{ }^{3-}$ ions.