An equimolar mixture of H2 and D2 effuses through an orifice (small hole) at a certain temperature,
Calculate the composition (in mole fractions) of the
gases that pass through the orifice. The molar mass
of D, is 2.014 g/mol. Answers are .586 and .414 but I need help getting there.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.

that's what i got you can count the number of atoms