Initially a gas of diatomic molecules is contained in a cylinder of...

${P}_{1} = {P}_{1}$
${v}_{1} = {v}_{1}$
${T}_{1} = 250$
${n}_{1} = {n}_{0}$
${n}_{2} = 0 . 75{n}_{0} + 2 \times 0 . 25{n}_{0} = 1 . 25no$
${v}_{2} = 2{V}_{1}$
${T}_{2} = 2000$
${P}_{1}{V}_{1} = {n}_{1}{RT}_{1}$
${P}_{2}{V}_{2} = {n}_{2}{RT}_{2}$
${P}_{1}{V}_{1} = {n}_{0}R \times 250$
${P}_{2}\left(2{V}_{1}\right) = \left(. 25{n}_{0}R ( 2000 )\right)$
equation $( 1 ) / ( 2 )$
$\dfrac{{P}_{1}}{2{P}_{2}} = \dfrac{250}{1 . 25 \times 2000}$
$\dfrac{{P}_{1}}{{P}_{2}} = \dfrac{1}{5}$
$\dfrac{{P}_{2}}{{P}_{1}} = 5$