The disease known as fluorosis is caused by the reaction of excess fluorine in the body with which of the following?

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?

The electronic configuration of a metal is $1s^2 2s^2 2p^6 3s^1$. The formula of its oxide is:

Sodium chloride imparts a golden yellow flame in a Bunsen burner. What can be inferred from this?

$STATEMENT-1$: Alkali metals dissolve in liquid ammonia to give a blue solution because
$STATEMENT-2$: Alkali metals in liquid ammonia give solvated species of the type $[M(NH_3)_n]^{+}$ ($M=$ alkali metals).

White metal is an alloy of