Arrange the following compounds in the increasing order of their thermal stability. Identify the correct sequence.
$I - K_2CO_3, II - MgCO_3, III - CaCO_3, IV - BeCO_3$

Which of the following elements liberate $H_2$ gas on reaction with $NaOH$?

When an alkali metal dissolves in liquid ammonia,the solution can acquire different colours. Explain the reasons for this type of colour change.

Among the nitrates of alkali metals,which one can be decomposed to its oxide on strong heating?

$A$ metallic oxide reacts with water to form its hydroxide,hydrogen peroxide,and also liberates oxygen. The metallic oxide could be

Identify the correct statements from the following :
$I$. Tendency to form halide hydrates gradually increases from $Be$ to $Ba$ down the group.
$II$. Tendency to form stable superoxides increases from $Li$ to $Cs$ down the group.
$III$. Low solubility of $LiF$ is due to its high lattice energy.
$IV$. Solubility of carbonates of group-$2$ elements increases down the group.