d
\(\begin{array}{l}
Change\,in\,momentum\\
\Delta P = \frac{P}{{\sqrt 2 }}\hat j + \frac{P}{{\sqrt 2 }}\hat j + \frac{P}{{\sqrt 2 }}\hat i - \frac{P}{{\sqrt 2 }}\hat i\\
\Delta P = \frac{{2P}}{{\sqrt 2 }}\hat j = {I_H}\,molecule\\
 \Rightarrow \,{I_{wall}} =  - \frac{{2P}}{{\sqrt 2 }}\hat j
\end{array}\)

\(\begin{array}{l}
pressure,P\\
 = \frac{F}{A} = \frac{{\sqrt 2 P}}{A}n\,\,\,\,\,\left( {\,n = no.of\,particles} \right)\\
 = \frac{{\sqrt 2  \times 3.32 \times {{10}^{ - 27}} \times {{10}^3} \times {{10}^{23}}}}{{2 \times {{10}^{ - 4}}}}\\
 = 2.35 \times {10^3}N/{m^2}
\end{array}\)