JEE Advanced levelOne or more correct optionsDifficulty 3 of 3ia072
A solution contains 0.010M each of BrX− and CrOX4X2−. Solid AgNOX3 is added slowly (no volume change). Ksp(AgBr)=5.0×10−13, Ksp(AgX2CrOX4)=1.1×10−12. Select the correct statement(s).
AAgBr precipitates before AgX2CrOX4
BAgX2CrOX4 starts to precipitate at [AgX+]=1.05×10−5M
CWhen AgX2CrOX4 just starts, [BrX−] left is 1.4×10−6M
DAt that stage more than 99.99% of the bromide has been precipitated
Answer: A, B, D
AgBr needs [AgX+]=5.0×10−13/0.010=5.0×10−11M, far below the 1.1×10−12/0.010=1.0×10−5M needed for AgX2CrOX4. At the latter value [BrX−]=4.8×10−8M (99.9995 % precipitated), so the third statement (wrong value) is false.