Answer : The number of moles of carbonate ion, 
 produced are, 0.207 moles.
 produced are, 0.207 moles.
Explanation : Given,
Moles of sodium carbonate = 0.207 mol
As we know that when sodium carbonate dissolved in water then it dissociates to give 2 sodium ion and 1 carbonate ion.
The balanced chemical reaction will be:

From the balanced chemical reaction we conclude that,
As, 1 mole of sodium carbonate dissociate to give 1 moles of carbonate ion, 

So, 0.207 mole of sodium carbonate dissociate to give 0.207 moles of carbonate ion, 

Thus, the number of moles of carbonate ion, 
 produced are, 0.207 moles.
 produced are, 0.207 moles.