Answer:
Take account the molar mass of this compound (first of all u should know the formula, S2F10). As the molar mass is 254,1 g/mol you will know that in 1 mol, you have 254,1 g so make a rule of three to solve it. If we find 254,1 g of S2F10 in 1 mol, 2,45 g of it are in 9,64 *10^-3 moles. That is the right number.
Explanation:
