Final answer:
To recover 1 mg of lead from water with a concentration of 1 ppm, you would need 1 L of water.
Step-by-step explanation:
If the lead concentration in water is 1 ppm (parts per million), this means that there is 1 milligram of lead (mg) per liter of water (L). Therefore, to recover 1 mg of lead, you would need to extract it from 1 L of water. This means that there is 1 part of lead in 1 million parts of water. Since 1 ppm is equivalent to 1 mg/L (milligram per liter), we can recover 1 mg (milligram) of lead from 1 liter of water. The correct answer is C: 1.