Aspherical balloon is 40 ft in diameter and surrounded by air at 60°f and 29.92 in hg abs.(a) if the balloon is filled with hydrogen at a temperature of 70°f and atmospheric pressure, what total load can it lift? (b) if it contains helium instead of hydrogen, other conditions remaining the same, what load can it lift? answers (a) 2381 lb; (b) 2209 lb

It's obviously b because the more helium it has, the lighter it is...

For the answer to the questions above, I'll give the formulas so that you can answer the equation easily.

These are the equations you need to solve this: 

Lift Load = Buoyancy Force = (Weight of air inside balloon if it were filled with outside dry air) - (Weight of actual gas inside balloon) 

Weight of gas inside balloon = (density of gas) (acceleration of gravity at earth's surface) (balloon volume) 

Density of gas = (absolute pressure)(Molecular Weight of Gas) / [(Specific Gas Constant)(absolute temperature)] 

Balloon Volume = (4/3) π (balloon radius)^3 

All you have to do is substitute them with the values.