Question

The ppm level of $F^{-}$ in a 500 g sample of a tooth paste containing 0.2 g $F^{-}$ is

• A. 400
• B. 1000
• C. 250
• D. 200

Answer 1

Answer: (A)

$ppm=\frac{wt.ofsolute}{wt.ofsolvent}\times 10^6$
$=\frac{0.2}{500}\times 10^6=400$