Which of the following properties is not true for an alkali metal?

Carnallite does not contain

Which of the following statements about the sulphates of alkali metals is correct?

Write the decreasing order of hydration enthalpy of alkali metal ions.

Name the industrially important compounds of $Sodium$.

Magnesium is burnt in the air to form $A$ and $B$. When $B$ is hydrolyzed,$C$ and $D$ are formed. $D$ is the reactant in the manufacture of nitric acid by Ostwald's process. What is $C$?