25. A solution is made by combining $4.00 \mathrm{~g}$ of sugar and $100 \mathrm{~g}$ of water. What is the concentration in $\% \mathrm{~m} / \mathrm{m}$ ? A. $0.0385 \%$ B. $0.0400 \%$ C. $3.85 \%$ D. $4.00 \%$

Step 1 ：The concentration in %m/m (mass/mass) is calculated by the formula: \(% m/m = \frac{mass of solute}{mass of solution} \times 100%\)

Step 2 ：The mass of the solute (sugar) is 4.00 g and the mass of the solution is the sum of the mass of the solute and the solvent (water), which is 4.00 g + 100 g = 104 g.

Step 3 ：So, the concentration in %m/m is: \(% m/m = \frac{4.00 g}{104 g} \times 100% = 3.85 %\)

Step 4 ：\(\boxed{3.85 \%}\) is the final answer.