$NH_3 + O_2 \xrightarrow[\Delta ]{Pt} A + H_2O;$ $A + O_2 \to B;$ $B + O_2 + H_2O \to C$
$A, B$ and $C$ are

The reaction of nitric oxide with ozone produces which gases?

Which element forms unstable trihalides?

Rationalize the given statements and provide chemical reactions:
$1$. Lead $(II)$ chloride reacts with $Cl_2$ to give $PbCl_4$.
$2$. Lead $(IV)$ chloride is highly unstable towards heat.
$3$. Lead is known not to form an iodide,$PbI_4$.

$A$ obtained by Ostwald's method involving air oxidation of $NH_3$,upon further air oxidation produces $B$. $B$ on hydration forms an oxoacid of Nitrogen along with evolution of $A$. The oxoacid also produces $A$ and gives positive brown ring test.

$NH_3$ can not be obtained by