The equilibrium p-xyloquinone + methylene white $\rightleftharpoons \mathrm{p}$-xylohydroquinone + methylene blue may be studied conveniently by observing the difference in colour methylene white and methylene blue. One m mol of methylene blue was added to 1L of solution that was 0.24 M in 0.012M p-xylohydroquinone and 0.012 M in p-xyloquinone. It was then found that 4% of the added methylene blue was reduced to methylene white. What is the equilibrium constant of the above reaction? The equation is balanced with one mole each of 4 substances.