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

Give any two uses of washing soda.

Lithium shows diagonal relationship with element $X$ and aluminum with $Y$. $X$ and $Y$ respectively are

The metal which does not form ammonium nitrate by reaction with dilute nitric acid is

What is the product formed when sodium is heated in a current of dry ammonia?

Consider the following statements.
$I$. $Cs^{+}$ ion is more highly hydrated than other alkali metal ions.
$II$. Among the alkali metals,only lithium forms a stable nitride by direct combination with nitrogen.
$III$. Among the alkali metals $Li, Na, K, Rb$,the metal $Rb$ has the highest melting point.
$IV$. Among the alkali metals $Li, Na, K, Rb$,only $Li$ forms peroxide when heated with oxygen.
Select the correct statement.