Question

If an ideal gas does positive work on its surroundings, we may assume, with regard to the gas:
A. Volume increases
B. Internal energy decreases
C. Pressure decreases
D. Temperature increases
E. Pressure increases

Answer 1

To do positive work, you must push in the direction of motion. That requires an increase of volume as the walls of the balloon move out :)

It could be that the internal energy decreases at the same time but you might be putting heat in.