Answer:
V₂ = 145.35 L
Step-by-step explanation:
Given data:
Initial volume = 400 L 
Initial pressure = 300 mmHg (300/760 =0.39 atm) 
Initial temperature = 20 °C (20 +273 = 293 K) 
Final temperature = 273 K
Final volume = ?
Final pressure = 1 atm
Solution:
Formula: 
P₁V₁/T₁ = P₂V₂/T₂ 
P₁ = Initial pressure 
V₁ = Initial volume 
T₁ = Initial temperature 
P₂ = Final pressure 
V₂ = Final volume 
T₂ = Final temperature 
P₁V₁/T₁ = P₂V₂/T₂ 
V₂ = P₁V₁T₂ /T₁ P₂
V₂ = 0.39 atm × 400 L × 273 K / 293 K × 1 atm
V₂ = 42588 atm.L.K /293 K.atm
V₂ = 145.35 L