$A$ tetra-atomic molecule $(A)$ on reaction with excess oxygen produces substance $(B)$. $(B)$ is a dehydrating agent. The substances $(A)$ and $(B)$ respectively will be:

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

Laughing gas is prepared by heating

$A$ $p$-block element $(E)$ and hydrogen form a binary cation $(EH_{x}^{+})$,while $EH_{3}$ on treatment with $K_{2}HgI_{4}$ in alkaline medium gives a precipitate of basic mercury$(II)$amido-iodine. Given below are first ionisation enthalpy values $(kJ \ mol^{-1})$ for the first element of each group $13, 14, 15$,and $16$. Identify the correct first ionisation enthalpy value for element $E$.

Concentrated $HNO_3$ is a yellow-colored liquid due to:

When bismuth chloride is poured into a large volume of water,the white precipitate produced is