Answer: 3.
Explanation:
1) CaCl₂ is a ionic compound formed by 1 ions of calcium, Ca²⁺, and 2 ions of chlorine, Cl⁻.
2) The ionic compounds dissociate in water (some dissociate more than others) into its ions.
3) Each unit of CaCl₂ dissolved will generate one Ca²⁺ one two Cl⁻, according to this equation:
CaCl₂ (aq) → Ca²⁺ + 2 Cl⁻
Note that if you add up the charges of the ions you end up with the same charge of the original formula: 2 + + 2 (1-) = 2 - 2 = 0. The original formula CaCl₂ is neutral (charge 0).
4) So in total, those are 3 ions, per each unit dissolved.
