Answer
6
Work Step by Step
Atomic weights (g/mol): $S: 32.06,\ F: 18.998$
Molar mass $F_2$: 38.00 g/mol
Mass of S: 1.256 g
Mass of the product: 5.722 g
Mass of fluorine $F_2$: 5.722 - 1.256 = 4.466 g
Number of moles:
S: $1.256/32.06=3.92\times10^{-2}\ mol$
$F_2$: $4.466/38.00=0.118\ mol\ F_2 = 0.235\ mol\ F$
Normalizing by the smallest amount of moles:
S: 1.0
F: 6.0
Empirical formula of the product: $SF_6$
Value of x: 6