Chemistry · May / June 2018 · Paper 12 · Question 4

Two gases, ammonia and hydrogen chloride, at an equal pressure, are allowed to enter the apparatus shown. [diagram: HCl(g) entering from left, NH3(g) entering from right, white solid forming inside tube] After a time, a white solid forms on the inside of the tube. Which statements explain why a white solid forms in the position shown? 1 Ammonia and hydrogen chloride react to form solid ammonium chloride. 2 Ammonia diffuses faster than hydrogen chloride. 3 Ammonia has a lower relative molecular mass than hydrogen chloride.

1. A1, 2 and 3
2. B1 and 2 only
3. C1 only
4. D2 and 3 only

As printed in the paper