According to the combined gas law: (P₁*V₁)/T₁=(P₂*V₂)/T₂, where P is the pressure, V is the volume and T is the temperature.
P₁=0.4 atm = 40530 Pa
V₁=21.7 L = 0.0217 m³
T₁=252 K
P₂=2 atm = 202650 Pa
T₂=323 K
V₂=?
We need to solve for V₂:
(P₁*V₁)/T₁=(P₂*V₂)/T₂
(T₂*P₁*V₁)/T₁=P₂*V₂
(T₂*P₁*V₁)/(T₁*P₂)=V₂, now we plug in the numbers and get:
V₂=0.00556 m³, and we can see that with increased temperature and pressure the volume V₂ has decreased.
When we transfer V₂=0.00556 m³ to liters we get that 0.00556 m³=5.56 L. That can be rounded up to V₂=5.6 L.