Answer:
The new volume would be 9 L
Step-by-step explanation:
Here, we want to get the new volume of the container
Mathematically, the volume and temperature of a given mass of gas is directly proportional according to Charles' law
We have that as:

where:
V1 is the initial volume which is 18 L
T1 is the initial temperature which is 420 K
V2 is the final volume that we want to calculate
T2 is the final temperature which is 210 K
Substituting the values, we have it that:
