The pressure : 1.536 atm
Further explanation
Same container=same volume⇒the volume is constant
Gay Lussac's Law
When the volume is not changed, the gas pressure in the tube is proportional to its absolute temperature
[tex]\tt \dfrac{P_1}{T_1}=\dfrac{P_2}{T_2}[/tex]
P₁=1 atm
T₁=20+273=293 K
T₂=450 K
the pressure :
[tex]\tt P_2=\dfrac{P_1.T_2}{T_1}\\\\P_2=\dfrac{1\times 450}{293}=\boxed{\bold{1.536~atm}}[/tex]
