0.10 M potassium chromatic is slowly added to a solution containing 0.40 M AgNO ₃ and 0.40 M Ba(NO ₃ ) ² . What is the Ag+ concentration when BaCrO ₄ just starts to precipitate? The K sp for Ag ₂ CrO ₄ and BaCrO4 are 1.1 × 10-12 and respectively.

6.5 × 10-5 M

3.2 × 10-4 M

1.3 × 10-4 M

6.1 × 10-2 M