A tooth paste containing fluoride in form of sodium mono fluoroortho phosphate Na₃PO₄F has 0.754 g sodium in 100 mL solution. Which of the following are correct for the given observation? 

Given, 100 ml contains 0.754 g sodium.

So, mass of compound in 100 ml solution is, $\frac{183\times 0.754}{69}=2.07g$

Molarity of solution is $\frac{2.07\times 10}{183} =0.11M.$

Mass of fluoride in 100 ml solution is $\frac{2.07\times 19}{183} =0.214g.$

Molecules of fluoride = $\frac{0.214}{19}\times {\mathrm{N}}_{\mathrm{A}}=6.8\times {10}^{21}.$