Answer:
5.6 L or 5600 mL
Step-by-step explanation:
This question asks for the use of combined gas law:
(P1)(V1) / (T1) = (P2)(V2) / (T2)
...where pressure (P) is in atm, volume (V) is in liters, and temperature (T) is in kelvin.
1400 ml is 1.4 L, and everything else is already in the right units.
(1 atm)(1.4 L) / (20 K) = (0.5 atm)(V2) / (40 K)
Just solve the equation for V2, and you get a new volume of 5.6 liters.
(1)(1.4) / (20) = (.5x) / (40)
1.4 / 20 = .5x / 40
2.8 = .5x
x = 5.6