Assertion $A$: Alkali metal elements impart characteristic colors to the flame in a flame test.
Reason $R$: They have very low ionization enthalpy.

The correct variation of the following properties of group $1$ elements $(M)$ ($Li$ to $Cs$) is:

Which of the following has the highest tendency to undergo the following reaction?
$M^{+}_{(g)} \xrightarrow{\text{aqueous medium}} M^{+}_{(aq)}$

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.

When $Na$ is heated at $300\,^oC$,it forms $X$. It absorbs $CO_2$ to form $Na_2CO_3$ and $Y$. What is $Y$?

$Al$ utensils should not be cleaned with materials containing washing soda because .............