4. Chemical bonding and molecular structure — Chemistry STD 11 Science — Question

$(I)$  $\begin{array}{*{20}{c}}
  {{{(C{H_3})}_3}Si - NB{H_2}} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,Si{{(C{H_3})}_3}} 
\end{array}$         $(II)$   $\begin{array}{*{20}{c}}
  {{{(C{H_3})}_3}C - NB{H_2}} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{{(C{H_3})}_3}} 
\end{array}$

For the given reaction, if the initial pressure is $450\,mm Hg$ and the pressure at time $t$ is $720\,mm\,Hg$ at a constant temperature $T$ and constant volume $V$. The fraction of $A ( g )$ decomposed under these conditions is $x \times 10^{-1}$. The value of $x$ is $......$.(nearest integer)

$\text{P}_4+3\text{OH}^-+3\text{H}_2\text{O}\xrightarrow{ \ \ \ \ \ \ \ }\text{PH}_3+3\text{H}_2\text{PO}^-_2$