Question

A sample of toothpaste weighting 500gm. On analysis was found to contain 0.2 gm of fluorine. The concentration of fluorine in ppm is

• A. 400
• B. 600
• C. 300
• D. 150

Answer 1

The correct option is A 400

500 — 0.2 g. fluorine
10⁶ — ?
$\frac{{10}^6\times 0.2}{500}=400ppm$