When $Mg$ burns in air,it produces

Which one on reaction with $NaOH$ solution gives inflammable gas?

Discuss the various reactions that occur in the Solvay process.

Sodium is produced by the electrolysis of a molten mixture of about $40\%$ $NaCl$ and $60\%$ $CaCl_2$ because

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.

State as to why:
$(a)$ a solution of $Na_2CO_3$ is alkaline?
$(b)$ alkali metals are prepared by electrolysis of their fused chlorides?
$(c)$ sodium is found to be more useful than potassium?