Question

A sample of sea water contains $5\times {10}^{-3}g$ of dissolved oxygen in $1kg$ of the sample. The concentration of $O_2$ in that sea water sample in ppm is:

• A. $5\times {10}^4$
• B. $5\times {10}^{-3}$
• C. $5\times {10}^{-2}$
• D. $5\times {10}^{-1}$
• E. $5$

Answer 1

Answer: (E)

$5$

Given, ${10}^{3}g\left(1kg\right)$ sample contains oxygen
$=5\times {10}^{-3}g$
$\therefore {10}^{6}g$ sample will contain oxygen
$=\frac{5\times {10}^{-3}g}{{10}^{3}g}\times {10}^{6}g$
$=5ppm$