Crown ethers and cryptands form:

The main salt soluble in sea water is

The sequence of ionic mobility in aqueous solutions is

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.

Which of the following alkali metals has the biggest tendency for the half reaction,$M \rightarrow M^{+} + e^-$?

Which metal bicarbonates do not exist in the solid state?
$(i) \, LiHCO_3$
$(ii) \, Ca(HCO_3)_2$
$(iii) \, Zn(HCO_3)_2$
$(iv) \, AgHCO_3$