Solution:

The solid XY decomposes into gaseous X and Y: XY(s) ⇌ X(g) + Y(g); K_p=4.1 (at 0˚C). If the reaction is carried out in a 22.4 L container, which initial amounts of X and Y will result in the formation of solid XY?
a) 5 mol X; 0.5 mol Y
b) 2.0 mol X; 2.0 mol Y
c) 1 mol X; 1 mol Y
d) none of the above