During the practical class you used 1.0 ml of 30% w/w hydrogen peroxide in your experiment in a final volume of 3 ml of the reaction mixture.
The final concentration of hydrogen peroxide in the reaction mixture was [a] % w/v
Note: the density of 30% w/w hydrogen peroxide is 1.11 g/ml. Use the relationship: % (w/w) x density = % (w/v). Answer with two significant figures. Do not type units or symbols.