Which of the following is the correct decreasing order of thermal stability of alkaline earth metal carbonates?

The compound$(s)$ of alkaline earth metals,which are amphoteric in nature is/are

From which of the following reactions can anhydrous $MgCl_2$ be prepared?

Identify the correct statements with respect to compounds of Beryllium:
$I$. Beryllium oxide is amphoteric in nature.
$II$. Beryllium hydride is formed by the reaction of beryllium with hydrogen.
$III$. Beryllium hydride is formed by the reaction of beryllium chloride with lithium aluminium hydride.
$IV$. Beryllium sulphate is the least soluble sulphate among the sulphates of alkaline earth metals.

The compound $A$ on heating gives a colourless gas and a residue that is dissolved in water to obtain $B$. Excess of $CO_2$ is bubbled through aqueous solution of $B$,$C$ is formed which is recovered in the solid form. Solid $C$ on gentle heating gives back $A$. The compound $A$ is:

The commercial name for calcium oxide is