What is the concentration of mercury in ppm if there are 321.4 μg mercury ions in a 4.50 L of water?

• A. 7.14x10^-1 ppm
• B. 7.14x10^-2 ppm
• C. 7.14x10^-3 ppm
• D. 7.14x10^-4 ppm
• E. 7.14x10⁴ ppm

Answer: (B)