Final answer:
The % concentration of sugar in the aqueous solution is 67%.
Step-by-step explanation:
To find the % concentration of sugar in the aqueous solution, we need to calculate the mass/mass percent concentration. This is given by the formula:
mass of solute / mass of solution * 100%
In this case, the mass of the solute (sugar) is 268 g and the mass of the solution is 400 ml, which is equivalent to 400 g (since the density of water is 1 g/ml). Plugging these values into the formula:
268 g / 400 g * 100% = 67%
Therefore, the % concentration of sugar in the aqueous solution is 67%.