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

Among the following metals,which one has the lowest probable interatomic forces?

Which one of the following statements is not correct?

What is the formula of calcium cyanamide?

The catalyst used to convert sodium to sodium amide is

Statement $I$: An alloy of lithium and magnesium is used to make aircraft plates.
Statement $II$: The magnesium ions are important for cell-membrane integrity.
In the light of the above statements,choose the correct answer from the options given below.