Answer
Take account the molar mass of this compound (first of all u should know the formula, S2F10) so when u have the molar mass, you can get how many grams of it, are present in 2.15 moles. The right mass is 546,3 g.
Explanation:
Molar mass in the S2F10 should be, molar mass in S (32.06 x2) + molar mass of F (18.998 x 10) = 254,1 g/m
