Which of the following substances is a deliquescent ionic solid?

Pure $N_2$ gas is prepared by:

$A$ soft heavy metal melts at $30\ ^oC$ and is used in making heat-sensitive thermometers. The metal is:

Which oxide is alkaline?

Correct statements from the following are: $A$. Nitrogen in oxidation states from $+1$ to $+4$ disproportionates in acid medium. $B$. Nitrogen has the ability to form $d\text{--}p$ multiple bonds with itself and other elements with small size and high electronegativity. $C$. $N$-$N$ single bond is stronger than $P$-$P$ single bond. $D$. Nitrogen has highest density in its group due to small size. $E$. The maximum covalency of nitrogen is four since it has only four valence orbitals for bonding.

The reaction of $NO$ with $N_2O_4$ at $250 \ K$ gives :