The fluorides BF₃, AlF₃, SiF₄, and PF₅ are Lewis acids. The all form very stable fluoroanions when treated with lithium fluoride. In contrast, the three fluorides CF₄, NF₃, and SF₆ do not react with lithium fluoride. Explain by selecting all that apply.

a. CF₄ and NF₃ have no available orbitals on the inner atoms to form additional bonds.

b. CF₄ and NF₃ are also Lewis acids.

c. BF₃, AlF₃, SiF₄, and PF₅ all have the ability to form a new bond.

d. In SF₆, the inner atom is sterically crowded, preventing another F^- from approaching the S atom.

e. BF₃, AlF₃, SiF₄, and PF₅ all contain electron deficient inner atoms.