Dalton's law of partial pressures that
\(p =\left( n _{1}+ n _{2}\right) \frac{ RT }{ V }\)
\(p _{1}=\frac{ n _{1} RT }{ V }\)
\(p _{2}=\frac{ n _{1} RT }{ V }\)
\(n _{1}= n _{2}=\frac{1}{4}\)
\(p _{1}= p _{2}\)
\(p _{1}= p _{2}=10\)
\(p _{1}=5 \; atm\)