Answer: The new volume is 2.1 L.
Step-by-step explanation:
Use the formula Boyle's law.

Here,
are the initial pressure and the final pressure and
are the initial and the final volumes.
As, it is given in the problem, a helium balloon has a volume of 2.00 L at 101 kPa. As the balloon rises, the pressure drops to 97.0 kPa.

Put P_{1}=101 kPa,V_{1}=2.00L and P_{2}=97.0 kPa.


Therefore, the new volume is 2.1 L.