The composition of an ideal gas mixture, by volume, is 30% nitrogen (N2), 30% oxygen (O2), and 40% hydrogen (H2). The mass fraction of oxygen, in percentage, is (round to nearest integer; for example if the answer is 14.6%, write 15; if the answer is 14.49% write 14; do not include the % symbol in your answer):

Explanation:

Since the gas mixture is ideal, the composition by volume is equal to the composition by moles.

Thus, the mole composition is:

Use a basis of 100 moles and find the mass of each gas, using its corresponding molar masss:

Total mass = 840g + 480g + 80g = 1,400g

Then, the mass fraction of oxgygen is the mass of oxygen divided by the total mass of the gas mixture:

Which in percentage is 34.29%.

Rounded to the nearest integer that is 34% ← answer