Explain the following:

Anhydrous calcium sulphate is used as drying agent.

Explain the following:

In the manufacture of $\mathrm{Mg}$ by carbon reduction of $\mathrm{MgO}$, the product is cooled in the steam of an inert gas.

Explain the following:

Why gypsum is added to cement?

${\mathrm{BaC}}_2+{\mathrm{N}}_2\stackrel{\mathrm{\Delta }}{⟶}\left(1\right)$
${\mathrm{CaC}}_2+{\mathrm{N}}_2\stackrel{\mathrm{\Delta }}{⟶}\left(2\right)$

($1$) and ($2$) are