Two balloons hold two different gases. The gases are held at the same pressure, volume, and temperature. Which quantity can differ between the two gases?

The quantity that can differ between the two gases is B. the mass of each gas.

The ideal gas law equation, PV = nRT, states that for a given pressure (P), volume (V), and temperature (T), the quantity of gas measured in moles (n) is constant. This means that option A is incorrect because the number of moles of each gas would be the same.

The molar volume (C) is calculated by dividing the volume by the number of moles of gas. Since the number of moles is the same for both gases, the molar volume would also be the same.

The gas constant, R, is a constant value regardless of the gas being used. It is the same for all gases and would not differ between the two gases. Therefore, option D is incorrect.

The mass of each gas (B) can differ between the two gases because different gases have different molar masses. The molar mass is the mass of one mole of a substance. Since the molar mass of each gas is different, the mass of each gas would also be different.

The answer is A. the number of moles of each gas. The number of moles of a gas is determined by its mass and molar mass, which can vary between different gases.