Question

The `K_(sp)` of `Ag_(2)CrO_(4), AgCl, AgBr` and AgI are respectively, `1.1 xx 10^(-12), 1.8 xx 10^(-10), 5.0 xx 10^(-13), 8.3 xx 10^(-17)`. Which one of the following salts will precipitate last if `AgNO_(3)` solution is added to the solution containing equal moles of NaCl, NaBr, NaI and `Na_(2)CrO_(4)`
A. AgCl
B. AgBr
C. `Ag_(2)CrO_(4)`
D. AgI

Answer 1

Correct Answer - C
`{:(K_(sp) " of " Ag_(2)CrO_(4),,= 1.1 xx 10^(-12)),(K_(sp) " of " AgCl,,= 1.8 xx 10^(-10)),(K_(sp) " of " AgBr,,= 5.0 xx 10^(-13)),(K_(sp) " of "AgI,,= 8.3 xx 10^(-17)),([Ag^(+)]^(2)[C],,= 1.1 xx 10^(-12)):}`
`[Ag^(+)] = sqrt((1.1 xx 10^(-12))/([C]))`
If we take [C] = 1 then the maximum requirement of `[Ag^(+)]` will be case of `Ag_(2)CrO_(4)`