Which of the following elements forms a superoxide when it reacts with oxygen?

Which one of the following fluorides of alkali metals has the highest lattice energy?

The correct order of electrical conductivity of alkali metal ions in their aqueous solution for $Cs^{+}$, $K^{+}$, $Na^{+}$, and $Li^{+}$ is:

When sodium is dissolved in liquid ammonia,a deep blue coloured solution is obtained. This colour of the solution is due to:

In the synthesis of sodium carbonate,the recovery of ammonia is done by treating $NH_4Cl$ with $Ca(OH)_2$. The by-product obtained in this process is

The following metal ion activates many enzymes,participates in the oxidation of glucose to produce $ATP$,and with $Na^+$,is responsible for the transmission of nerve signals.