Calculate the molarity of each ion in 0.300 M Na2SO4. Enter a zero for an ion that doesn't occur in the compound.

Question

______ M Na1+
______ 2 M S2-
______ 3 M O 2-
______ M SO42-

Answer 1

0.3M Na2SO4 means you have
0.3 moles Na2SO4/L soln.
So you will have 0.3M Na2SO4, 0.6M Na^+, 0.3M S, 4*0.3M O and 0.3M SO4^2-.
I have no idea what 2 M S2- or 3 M O 2- is.