Question

The concentration of a solution is ${10}^{-4}M$for$C{l}^{-},{10}^{-5}M$for$B{r}^{-}$ and${10}^{-3}M$for$I^{-}.$ $AgN{O}_3\left(s\right)$ is added slowly to the solution. The minimum concentration of $A{g}^{+}$ required to start precipitation of all three ions is:
[Given, $K_{sp\left(AgCl\right)}={10}^{-10},K_{sp\left(AgBr\right)}={10}^{-13},K_{sp\left(AgI\right)}={10}^{-17}$]

• A. ${10}^{-9}$
• B. ${10}^{-6}$
• C. ${10}^{-8}$
• D. ${10}^{-10}$

Answer 1

The correct option is B ${10}^{-6}$

For precipitation of $AgCl$,
$\left[A{g}^{+}\right]\left[C{l}^{-}\right]={10}^{-10}$

As the concentration of $C{l}^{-}={10}^{-4}$,

So, the minimum concentration of $A{g}^{+}$ required is ${10}^{-6}$.