Which of the following elements is the most metallic?

Why is nitrogen chemically inert?

In which of the following reactions,$NO_2$ is not liberated?

Which among the following oxides of nitrogen is a brown-coloured gas?

Regarding the hydrides of group $15$ elements $EH_{3}$ $(E = N, P, As, Sb, Bi)$, select the correct statement from the following:
$A$. The stability of hydrides decreases down the group.
$B$. The basicity of hydrides decreases down the group.
$C$. The reducing character increases down the group.
$D$. The boiling point increases down the group.
Choose the correct answer from the options given below:

The atomicity of phosphorus is $X$ and the $P-P-P$ bond angle in the molecule is $Y$. What are $X$ and $Y$?