The reaction between sulfur dioxide and oxygen is reversible.

2SO2(g) + O2(g) = 2SO3(g)
Kc=280mol^-1 dm^3 at 1000K


In an equilibrium mixture at 1000K the sulfur trioxide concentration is 6.00 mol dm^-3.


What is the sulfur dioxide concentration?


A) 0.175 mol dm^-3

B) 0.254 mol dm^-3

C) 0.318 mol dm^-3

D) 0.636 mol dm^-3