Q. The solubility products of $Al\left(\right.OH\left(\left.\right)_{3}$ and $Zn\left(\right.OH\left(\left.\right)_{2}$ are $8.5\times 10^{- 23}$ and $1.8\times 10^{- 14}$ respectively. If $NH_{4}OH$ is added to a solution containing $Al^{3 +}$ and $Zn^{2 +}$ ions, then substance precipitated first is:

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A

$Al\left(\right.OH\left(\left.\right)_{3}$

B

$Zn\left(\right.OH\left(\left.\right)_{2}$

C

Both together

D

None at all

Solution:

Ppt occurs when ionic product is greater than solubility product. Solubility of $Al\left(\right.OH\left(\left.\right)_{3}$ is lesser than $Zn\left(\right.OH\left(\left.\right)_{2}$

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