What is the molarity of 9. 33 g Na2S in 450 mL solution?

Molarity = moles/liter
moles = 9.33 g Na2S x 1 mole/78 g = 0.1196 moles
liters = 450 ml x 1L/1000 ml = 0.45 L
molarity = 0.1196 moles/0.45 L = 0.266 M = 0.27 M (2 sig figs)