Final answer:
The mole fraction of helium in a mixture of hydrogen and helium gases is a measure of concentration.
Step-by-step explanation:
The mole fraction of helium in a mixture of hydrogen and helium gases is a measure of concentration.
Mole fraction is a unit of concentration defined as the number of moles of a component of a solution divided by the total number of moles of all components. In a gas mixture, the mole fraction of helium represents the fraction of the total moles that is attributed to helium.
For example, if a mixture consists of 0.50 mol of helium and 1.00 mol of hydrogen, the mole fraction of helium would be 0.50/(0.50 + 1.00) = 0.333. Therefore, the mole fraction of helium indicates the concentration of helium in the mixture.