The reaction of water with sodium and potassium is

Why is $Li_{2}CO_{3}$ decomposed at a lower temperature whereas $Na_{2}CO_{3}$ at a higher temperature?

Which of the following is the correct arrangement in increasing order of solubility?

Beryllium is placed above magnesium in the second group. Beryllium dust,therefore,when added to $MgCl_2$ solution will:

The atomic radii of alkali metals $(M)$ lie in the order $Li < Na < K < Rb$,but the radii of $M^{+}$ ions in aqueous solution lie in the reverse order $Li^{+} > Na^{+} > K^{+} > Rb^{+}$. What is the reason for this reverse order (on going from $Li$ to $Rb$)?

When sodium is heated in excess of air,which of the following compounds are obtained?

$I. Na_3N$	$II. Na_2O$
$III. NaO_2$	$IV. Na_2O_2$