White metal is an alloy of

The compound which is not associated with the Solvay ammonia process for the production of $Na_2CO_3$ is:

$A$ metal when left exposed to the atmosphere for some time becomes coated with green basic carbonate. The metal in question is

Give points of similarities between lithium and magnesium.

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: $LiF$ is sparingly soluble in water.
Reason $R$: The ionic radius of $Li^{+}$ ion is smallest among its group members,hence it has the least hydration enthalpy.
In the light of the above statements,choose the most appropriate answer from the options given below.

Correct order of solubility is