How can you synthesise nitric oxide in the laboratory?

Account for the following observations:
$(A)$ $AlCl_3$ is a Lewis acid.
$(B)$ Though fluorine is more electronegative than chlorine yet $BF_3$ is a weaker Lewis acid than $BCl_3$.
$(C)$ $PbO_2$ is a stronger oxidizing agent than $SnO_2$.
$(D)$ The $+1$ oxidation state of thallium is more stable than its $+3$ state.

When ammonia is passed over heated $CuO$,it is oxidised to

Which of the following oxides is the most acidic?

Give the disproportionation reaction of $H_3PO_3$.

$A + H_2O \to B + HCl$
$B + H_2O \to C + HCl$
Compound $(A), (B)$ and $(C)$ will be respectively