Which substance is used as a smoke screen in warfare?

Which of the following allotropes of phosphorus is the most stable,has a graphite-like structure,and is a conductor of electricity?

Describe the methods of preparation,properties,and uses of dinitrogen gas $(N_2)$.

Nitrogen dioxide cannot be prepared by heating:

Which is the most thermodynamically stable allotropic form of phosphorus?

$P_4 + 3 NaOH + 3 H_2 O \xrightarrow{CO_2} 3 X + PH_3 \uparrow$
$X \xrightarrow{HCl_{(aq)}} Y + NaCl$
The incorrect statement about $Y$ is