Which of the following metals produces hydrogen gas on reacting with cold dilute nitric acid?

In $LiAlH_4$,metal $Al$ is present in

Which is most basic in character?

Assertion $(A): K, Rb$ and $Cs$ form superoxides. \\ Reason $(R):$ The stability of superoxides increases from $K$ to $Cs$ due to decrease in lattice energy.

Explain why alkali and alkaline earth metals cannot be obtained by chemical reduction methods?

The number of alkali metal$(s)$,from $Li$,$K$,$Cs$,$Rb$ having ionization enthalpy greater than $400 \ kJ \ mol^{-1}$ and forming stable super oxide is $.......$