What is the concentration in ppm of a 3.7 L solution (d = 1.00 g/mL) containing 4.21 * 10-7 kg of the pesticide DDT?

concentration in ppm of DDT = 0.011 ppm

Explanation:

since ppm of DDT = mg of DDT / Kg of solution (or μg of DDT / g of solution), then

concentration in ppm of DDT = 4.21 * 10⁻⁷ kg * 10⁶ mg/kg / (1.00 g/mL * 3.7 L * 1000 ml/L * 1 kg/1000gr) = 0.011 ppm

then

concentration in ppm of DDT = 0.011 ppm