Which of the following salts is not soluble in water?

On heating,which of the following releases $CO_2$ most easily?

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.

Assertion $A$: Barium is not required in the normal biochemical processes of the human body.
Reason $R$: Barium does not exhibit more than one oxidation state.

$A$ metal is burnt in air and the ash on moistening smells of $NH_3$. The metal is

$Be(OH)_2$ reacts with $Sr(OH)_2$ to yield an ionic salt. Choose the incorrect option related to this reaction from the following: