The chemical formula of feldspar is

Given below are two statements:
Statement $I$: Lithium and Magnesium do not form superoxide.
Statement $II$: The ionic radius of $Li^{+}$ is larger than the ionic radius of $Mg^{2+}$.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which of the following reacts with a solution of caustic soda upon heating to produce a combustible gas?

Match the following:

Metals	Flame color
$1$. $Li$	$a$. Crimson red
$2$. $K$	$b$. Violet
$3$. $Rb$	$c$. Red-violet
$4$. $Cs$	$d$. Blue

The stability of peroxides and superoxides of alkali metals increases as we go down the group. Explain giving reasons.

Write the decreasing order of hydration enthalpy of alkali metal ions.