What is caused by an excess of $Na^{+}$ ions in the human body?

Select the correct order :-

Write balanced chemical equations for the reactions between:
$(a)$ $Na_{2}O_{2}$ and water
$(b)$ $KO_{2}$ and water
$(c)$ $Na_{2}O$ and $CO_{2}$

Potassium superoxide on hydrolysis gives

Which of the following sets represents the alkali metals?

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