Answer: The volume of balloon at higher altitude is 631.3 L
Step-by-step explanation:
To calculate the volume when temperature and pressure has changed, we use the equation given by combined gas law. The equation follows:

where,
are the initial pressure, volume and temperature of the gas
are the final pressure, volume and temperature of the gas
We are given:
Conversion factor: 1 atm = 760 mmHg
![P_1=759mmHg=0.99atm\\V_1=50.0L\\T_1=22.3^oC=[273+22.3]K=295.3K\\P_2=0.0701atm\\V_2=?L\\T_2=-9.00^oC=[273-9]=264K](https://img.qammunity.org/2020/formulas/chemistry/college/hk82qh3oawmnl14io3xyvzp5hnhf4vynit.png)
Putting values in above equation, we get:

Hence, the volume of balloon at higher altitude is 631.3 L