Effusion of a 1:1 Mixture of Two Gases,represented by Unshaded

Multiple Choice

Effusion of a 1:1 mixture of two gases,represented by unshaded and shaded spheres in the diagram below,through a small pinhole produces the result shown below.The shaded spheres have a molecular mass of 20 amu.Which gas molecules have the higher average speed and what is the molecular mass of the unshaded molecules?

A) Unshaded molecules have higher average speed and molecular mass = 14 amu.
B) Unshaded molecules have higher average speed and molecular mass = 17 amu.
C) Unshaded molecules have lower average speed and molecular mass = 24 amu.
D) Unshaded molecules have lower average speed and molecular mass = 29 amu.