FeCl2(aq) is an ionic compound which will have the releasing of 2 Cl⁻ ions ions in water for every molecule of FeCl2 that dissolves.
FeCl2(s) --> Fe+(aq) + 2 Cl⁻(aq)
[Cl⁻] = 0.76 mol FeCl2/1L × 2 mol Cl⁻ / 1 mol FeCl2 = 1.5 M
The answer to this question is [Cl⁻] = 1.5 M
