Answer
a. 380 g of NaCl solution.
b. 16 mL of NaF solution
c. 240 mL of ethanol solution.
Work Step by Step
a. $2.0\%$ (m/m) $ NaCl $ solution : $$ 2.0 \space g \space NaCl = 100 \space g \space solution$$
$$7.50 \space g \space NaCl \times \frac{100 \space g \space solution}{2.0 \space g \space NaCl} = 380 \space g \space solution$$
b. $25\%$ (m/v) $ NaF $ solution : $$ 25 \space g \space NaF = 100 \space mL \space solution$$
$$4.0 \space g \space NaF \times \frac{100 \space mL \space solution}{25 \space g \space NaF} = 16 \space mL \space solution$$
c. $8.0\%$ (v/v) $ ethanol $ solution : $$ 8.0 \space mL \space ethanol = 100 \space mL \space solution$$
$$20.0 \space mL \space ethanol \times \frac{100 \space mL \space solution}{8.0 \space mL \space ethanol} = 240 \space mL \space solution$$
