3. 0 L
Explanation:
We’ll use P₁V₁/T₁ = P₂V₂/T₂
Because T₁ and T₂ are constant throughout, then the two cancel out and we are left with;
P₁V₁ = P₂V₂
We can bow replace the variables with given values form the question;
200 * 6.0 = 400 * V₂
200 * 6 / 400 = V₂
3 = V₂
= 3.0 L