You fill two balloons, A and B, with helium gas at the same temperature and pressure. You notice that balloon B has a larger volume than balloon A. What must be true about the masses of the gas inside each of the balloons?

The mass of the gas in balloon A is less than the mass of the gas in balloon B.

Explanation:

Here, we note that since the content of the balloons are the same, (helium) and the volume of balloon B is larger than that of balloon A, at the same temperature, then by the combined gas equation, we have

n = P·V/(R·T)

Where:

n = Number of moles of gas = Mass/(Molar Mass)

P = Pressure

V = Volume

T = Temperature

R = Universal gas constant

With T and P (Pressure of the surrounding of elastic balloon) being the same, then n is directly proportional to V

That is if V₁ > V₂ then n₁ > n₂ and the mass of balloon A is less han the mass of balloon B because n is directly proportional to the mass as the molar mass is the same in both balloons.