Give two uses of $Ca(OH)_2$.

Which of the following alkaline earth metals does not exhibit colour when heated in a flame?

The following compounds have been arranged in order of their increasing thermal stabilities. Identify the correct order.
$K_2CO_3$ $(I)$
$MgCO_3$ $(II)$
$CaCO_3$ $(III)$
$BeCO_3$ $(IV)$

Give a detailed explanation of the oxoacid salts of alkaline earth metal elements.

$A$ compound $x$ on heating gives a colourless gas. The residue is dissolved in water to obtain $y$. Excess $CO_2$ is bubbled through the aqueous solution of $y$ and $z$ is formed. $z$ on gentle heating gives back $x$. The compound $x$ is:

The thermal stability of $BaCO_3$,$CaCO_3$,$SrCO_3$,and $MgCO_3$ decreases in the order: