$P_4O_{10}$ is not used to dry $NH_3$ gas because:

Which metal is used in radiation shields?

What is catenation?

An example of a neutral oxide is

$FeS_2$ is

Reaction of $NaCl$ with conc. $H_2SO_4$ liberates a gas,$X$ that turns moist blue litmus paper red. When gas $X$ is passed into a test tube containing egg shell powder suspended in water,another gas,$Y$ is generated which when passed through lime water makes it milky. The gases $X$ and $Y$,respectively,are