What is obtained when sodium metal is heated in a stream of dry ammonia?

How many of the following metals give oxides and nitrides when burnt in air?
$Be, Na, Mg, Ba, Sr, Li, K$

As compared to lithium,sodium reacts quickly with water because

Which of the following is $NOT$ present in baking powder?

Which one of the following compounds in aqueous solution gives a white precipitate with perchloric acid?

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 $C$?