Final answer:
The volume of the balloon at constant pressure when heated to 323 K is 7.10 L.
Step-by-step explanation:
According to Charles' law, the volume of a gas is directly proportional to its temperature at constant pressure. To find the new volume of the balloon, we can use the formula:
 
V1/T1 = V2/T2
 
Given:
 
- V1 = 6.0 L
- T1 = 273 K
- T2 = 323 K
 
Substituting the values into the formula, we have:
 
6.0 L/273 K = V2/323 K
 
Solving for V2:
 
V2 = (6.0 L * 323 K) / 273 K = 7.10 L
 
Therefore, the volume of the balloon at constant pressure when heated to 323 K is 7.10 L (option A).