If sea water (density 1.03 g mL⁻¹) contains 5.8 g of dissolved O₂ per 10⁶ g of water, the concentration is best expressed as:
- 5.8 M
- 5.8% by mass
- 5.8 ppm
- 5.8 ppb
Show answer and solution
Correct answer: C. 5.8 ppm
Trace concentrations are expressed in **parts per million (ppm) = (mass of component / total mass) × 10⁶**.
5.8 g per 10⁶ g = **5.8 ppm**.