How many moles of MgS2O3 are in 179 g compound?

Answer 1

Molar mass MgS₂O₃ = 136.4 (add up atomic masses of the elements)

Calculation of moles:

179 g MgS₂O₃ x 1 mol / 136.4 g = 1.31 moles MgS₂O₃ (3 sig. figs.)