How many moles of ions are in the following?

Question

(a) 0.0245 g AgNO3

(b) 0.182 mol K2CrO4

(c) 0.630 g Ba(OH)2

(d) 1.48 X 10^-9 mol Na2CO3

Answer 1

moles = mass / mol_mass
so look up the molar mass for each compound and just divide as needed.
I suspect (d) is garbled.

Answer 2

d. So you have 2*1.48E-9 mols Na^+
and 1.48E-9mols [CO3]^2-