Answer: The number of moles of gas in balloon is 1.69 moles
Step-by-step explanation:
To calculate the number of moles of gas, we use the equation given by ideal gas which follows:

where,
P = pressure of the gas = 2.20 atm
V = Volume of the gas = 18.9 L
T = Temperature of the gas =
![27.1^oC=[27.1+273]=300.1K](https://img.qammunity.org/2021/formulas/chemistry/middle-school/6my0z9tdzesbsr4om6u1o7hznllayqbhlv.png)
R = Gas constant =

n = number of moles of gas = ?
Putting values in above equation, we get:

Hence, the number of moles of gas in balloon is 1.69 moles