In the Ostwald's process for the manufacture of $HNO_3$,the catalyst used is

$Pb + \text{Dil. } HNO_3 \xrightarrow{\text{Warm}} P + Q\uparrow + H_2O$
Incorrect statement for $Q$ is

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T$:
$\underline{P}Cl_3 + H_2O \longrightarrow H_3PO_3 + HCl$

Which of the following oxides is the least acidic?

Why does $R_{3}P=O$ exist but $R_{3}N=O$ does not ($R=$ alkyl group)?

Which element of group $-15$ forms the most basic hydride with hydrogen?