At 2200 k the equilibrium constant for the reaction below

Question

At 2,200 K, the equilibrium constant for the reaction below is K_c=11.3.

Br₂(g) --> 2 Br(g)

What is the percent dissociation of Br₂ at 2,200 K, if the initial concentration of Br₂ is 1.25mol/L?

Give your answer accurate to two significant figures. Do not include the % sign as part of your answer.

Hint: If the initial concentration of Br₂ is C_o and the concentration of Br₂ decreases by x (because of dissociation), then the percent dissociation of Br₂ is equal to 100(x/C_o).