Which of the following combinations will produce $H_2$ gas?

What happens if the concentration of $Na^{+}$ ions increases in the body?

Which of the following is thermally decomposable?

What is the general formula of halide salts of alkali metals if $M$ is a metal atom and $X$ is a halogen atom?

Which of the following is not correctly matched?

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.