Can any body help me with this baby questions plzzzzzz?

Question

1..If a tube contains 1.2g of Snf2 then how do you calculate the mass of fluorine in this tube.

2. And how can a fluorine atom change into a fluoride ion, F-?

Answer 1

1 mol of SnF2 = 157 g which contains 38 g of fluorine!

157 g --------- 38 g fluorine

1.2 g ----------- x g fluorine

x = (1.2 * 38) / 157 = approximately 0.29 g or 290 mg of fluorine.