\(x_{2}=\frac{p_{o}-p_{s}}{p_{o}}\)
Substitute the given values in the above equation.
\(\frac{\left(\frac{0.5}{65}\right)}{\left(\frac{158}{154}\right)}=\frac{143-p_{s}}{143}\)
After solving,
\(p_{s}=141.93 \,mm\, Hg\)
$\left(\mathrm{R}=0.083 \mathrm{~L}\right.$ bar mol-1 $\mathrm{K}^{-1}$ નો ઉપયોગ કરો)