<u>Answer:</u> The volume of balloon at higher altitude is 631.3 L
<u>Explanation:</u>
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:
<u>Conversion factor:</u> 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://tex.z-dn.net/?f=P_1%3D759mmHg%3D0.99atm%5C%5CV_1%3D50.0L%5C%5CT_1%3D22.3%5EoC%3D%5B273%2B22.3%5DK%3D295.3K%5C%5CP_2%3D0.0701atm%5C%5CV_2%3D%3FL%5C%5CT_2%3D-9.00%5EoC%3D%5B273-9%5D%3D264K)
Putting values in above equation, we get:

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