Why does lithium show anomalous behavior?

The useful by-products obtained in the $Solvay$ process of manufacturing sodium carbonate are:

State the reasons for the following:
$(a)$ Why is a solution of $Na_{2}CO_{3}$ alkaline?
$(b)$ Why are alkali metals prepared by the electrolysis of their fused chlorides?
$(c)$ Why is sodium found to be more useful than potassium in biological systems?

Which of the following statements is not correct for the element having electronic configuration $1s^2, 2s^2 2p^6, 3s^1$?

$Sodium$ metal is highly reactive and cannot be stored under:

When $Mg$ burns in air,it produces