Question

A sea water sample contains $8\times {10}^{-3}$ g of dissolved oxygen per kilogram. What is the concentration of oxygen in parts per billion?

• A. $8ppb$
• B. $8\times {10}^{-3}ppb$
• C. $8000ppb$
• D. $800ppb$

Answer 1

The correct option is C $8000ppb$

$1000g$ of sea water contains $8\times {10}^{-3}g$ of oxygen.
concentration in ppb $=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times {10}^9=\frac{8\times {10}^{-3}}{{10}^3}\times {10}^9=8000$