Question

Let a sea water sample contains $8\times {10}^{-2}$ g of dissolved oxygen per kilogram. What is the concentration of oxygen in parts per billion?

• A. $8\text{ppb}$
• B. $8\times {10}^3\text{ppb}$
• C. $8000\text{ppb}$
• D. $80000\text{ppb}$

Answer 1

The correct option is D $80000\text{ppb}$

$1000$ g of sea water contains $8\times {10}^{-2}$ g of oxygen.
Therefore,
concentration in ppb $=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times {10}^9=\frac{8\times {10}^{-2}}{{10}^3}\times {10}^9=80000$