Which one of the following elements is unable to form MF63- ion?
- Ga
- Al
- B
- In
Answer
(3) B
Solution
As per NCERT, boron has no d orbitals in its valence shell (only 2s and 2p) ⇒ its maximum covalency is 4 (e.g. [BF4]-).
Al, Ga and In have vacant d orbitals ⇒ they can expand their covalency to 6 and form [MF6]3- (e.g. [AlF6]3-).
∴ B cannot form BF63-.
Answer: (3)