Multiple choice

Equal masses of methane and hydrogen are mixed in an empty container at ${25}^{o}C$. The fraction of the total pressure exerted by hydrogen is:

  1. $\cfrac{1}{2}$
  2. $\cfrac{8}{9}$
  3. $\cfrac{1}{9}$
  4. $\cfrac{16}{17}$
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B Correct answer
Explanation

Equal masses m. Moles of CH4 = m/16. Moles of H2 = m/2. Total moles = m/16 + 8m/16 = 9m/16. Mole fraction of H2 = (m/2) / (9m/16) = (m/2) * (16/9m) = 8/9.

AI explanation

Assume equal masses of methane and hydrogen are 16 grams each, which gives 1 mole of methane and 8 moles of hydrogen. According to Dalton's law of partial pressures, the fraction of total pressure exerted by a gas equals its mole fraction. The mole fraction of hydrogen is 8 divided by the total moles of 9, resulting in a pressure fraction of 8/9.

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