To answer this question, we have to use the Charles' Law of gases, that states the following:
[tex]\frac{V1}{T1}=\frac{V2}{T2}[/tex]
In this case, we know the values of T1, V1 and T2 and we have to find V2:
[tex]V2=\frac{V1T2}{T1}[/tex]
Replace for the given values and find V2:
[tex]\begin{gathered} V2=\frac{10.5L\cdot256K}{311K} \\ V2=8.64L \end{gathered}[/tex]
It means that the volume of the balloon outside is 8.64L.
