Calcium nitrate solution contains 0.5 mol of positive ions. The number of negative ions is equal.

So, we initially know that a calcium nitrate solution contains 0.5 mol of positive ions.

Let’s start by writing down the chemical formula for calcium nitrate.

Ca (NO3) 2.

Now let’s write down the dissociation reaction to see how this solution decomposes into positive and negative ions.

Ca (NO3) 2 ⇄ Ca2 + + 2NO3 -.

After examining the resulting reaction, we see that the number of anions we got is 2 times more than the number of cations.

We are looking for the number of cations:

2 * 0.5 mol = 1 mol.

Answer: 1 mole.