### Perfect (ideal) gases (4 part question)

Suppose your balloon has a radius of 3 m and that it is a spere when inflated. a.) how much H is needed to inflate it to a pressure of 1 atm at an ambient T of 25 celsius @ sea level? b.) what mass can the balloon lift @sea level, where the density of air is 1.22 kg m^-3 ? c.) what would be the payload if helium were used ins