The second one, air is a poor conductor. If it weren't it wouldn't be used as such in construction. It's not the best insulator, but is quite efficient, and much cheaper to include a layer of air inside a wall than to add additional layers of asbestos :)
The control group is the independent variable and the experimental group is the dependent due to change during the experiment. The experimental group will usually rely on another variable in the experiment for change.
Answer:

Explanation:
By ideal gas equation law we know that
PV = nRT
now we know that when balloon rises to certain level then the number of moles will remains same
so we can say


now plug in all data to find the final volume of the balloon


