In which of the following ranges does nitrogen exhibit its various oxidation states?

Which blue liquid is obtained on reacting equimolar amounts of two gases at $-30\,^oC$?

On heating,compound $(A)$ gives a gas $(B)$ which is a constituent of air. This gas,when treated with $H_{2}$ in the presence of a catalyst,gives another gas $(C)$ which is basic in nature. $(A)$ should not be:

Identify the reactions in which $N_2$ is liberated.
$a. \ (NH_4)_2SO_4 + NaOH \longrightarrow$
$b. \ NH_3 + Cl_2 \longrightarrow$ (excess $Cl_2$ is not specified,but $N_2$ is formed when $NH_3$ is in excess)
$c. \ (NH_4)_2Cr_2O_7 \xrightarrow{\Delta}$
$d. \ NH_4NO_3 \xrightarrow{\Delta}$
$e. \ NH_4Cl_{(aq)} + NaNO_{2_{(aq)}} \longrightarrow$

What is produced when $HNO_3$ reacts with $P_4O_{10}$?

How is nitrogen prepared in the laboratory? Write the chemical equations of the reactions involved.