$BeO$ reacts with $HF$ in the presence of ammonia to give $[A]$,which on thermal decomposition produces $[B]$ and ammonium fluoride. The oxidation state of $Be$ in $[A]$ is $.....$.

What is the chemical formula for Plaster of Paris?

Which substance imparts a green color to the burner flame?

Which of the following is least soluble?

Assertion : Both $Be$ and $Al$ can form complexes such as $BeF_4^{2-}$ and $AlF_6^{3-}$ respectively,$BeF_6^{3-}$ is not formed.
Reason : In case of $Be$,no vacant $d-$ orbitals are present in its outermost shell.

Thermal decomposition of which of the salt listed below yields a basic and an acidic oxide simultaneously?