What is the relative rate of diffusion of ammonia to hydrogen chloride, both in gaseous states?
No answer is correct, but "A" is  closest to the correct answer.  Heavier molecules diffuse slower than lighter ones because the same amount of thermal energy has to move more mass.  However, this relation (diffusion rate is inversely proportional to the square root of molecular weight) actually leads to 44 seconds not 64.  The professor who told you "D" probably misunderstood that in the second chamber there is HCl (acidic) instead of ammonia (basic).