$NaHCO_3$ can be manufactured by Solvay's process but $K_2CO_3$ cannot be prepared because

Given below are two statements:
Statement $I$: The chlorides of $Be$ and $Al$ have $Cl^{-}$-bridged structure. Both are soluble in organic solvents and act as Lewis acids.
Statement $II$: Hydroxides of $Be$ and $Al$ dissolve in excess alkali to give beryllate and aluminate ions.
In the light of the above statements,choose the correct answer from the options given below.

$A$ metal $(A)$ on heating in nitrogen gas gives compound $(B)$. $(B)$ on treatment with $H_{2}O$ gives a colourless gas which when passed through $CuSO_{4}$ solution gives a dark blue-violet coloured solution. $(A)$ and $(B)$ respectively,are

The lattice energy (numerical value) of alkali metal chlorides is in the order:

Hydrogen,by donating one electron,forms $H^+$. In this property,it resembles

The atomic radii of the alkali metals follow the order