Which of the following is most stable?

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.

Which element from the following rapidly loses its luster in air and tarnishes?

$A$ piece of magnesium ribbon is heated to redness in an atmosphere of nitrogen and on cooling with water,the evolved gas is

Which of the following compounds is obtained as a by-product in the synthesis of sodium carbonate by the Solvay process?

The golden yellow colour associated with $NaCl$ in a Bunsen flame can be explained on the basis of