Consider the reactions (not balanced)
\[
BF_3 + NaH \xrightarrow{450K} A + NaF
\]
\[
LiH + A \longrightarrow Li^{+}[X]^{-}
\]
The hybridisation involved in $[X]^{-}$ is
Show Hint
Important boron species:
\[
BF_3 \rightarrow B_2H_6 \rightarrow BH_4^-
\]
\[
BH_4^- \text{ is tetrahedral and } sp^3 \text{ hybridised.}
\]