Solid Potassium Chromate (K₂CrO₄)is Slowly Added to a Solution Containing $1.2 \times 10 ^{- 10} \text {, }$

Multiple Choice

Solid potassium chromate (K₂CrO₄) is slowly added to a solution containing 0.50 mol L^-1 AgNO₃ and 0.50 mol L^-1 Ba(NO₃) ₂.What is the Ag⁺ concentration when BaCrO₄ just starts to precipitate? The K_sp for Ag₂CrO₄ and BaCrO₄ are 1.1 × 10^-12 and $1.2 \times 10 ^{- 10} \text {, }$ respectively.

A) 6.5 × 10^-5 mol L^-1
B) 1.3 × 10^-4 mol L^-1
C) 3.2 × 10^-4 mol L^-1
D) 6.8 × 10^-2 mol L^-1