Solubility Product

Solubility Product MDCAT MCQs with answers

9 past paper MCQs on Solubility Product, from the Chemical Equilibrium unit of MDCAT Chemistry. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

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1.Precipitation occurs if the ionic concentration is: (MDCAT 2022)

  1. greater than $K_{sp}$
  2. less than $K_{sp}$
  3. equal to $K_{sp}$
  4. present in any amount
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Correct answer: (a) greater than $K_{sp}$

The solution can hold only as much as $K_{sp}$ allows, so anything above that comes out as solid.

2.The solubility of PbS at 25°C is 4.0 × 10−28. Then ionic concentration will be: (NUMS MDCAT 2024)

  1. 4x10−14
  2. 2x10−14
  3. 1x10−14
  4. 3.0x10−10
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Correct answer: (b) 2x10−14

For a one to one salt $K_{sp}=s^2$, so $s=\sqrt{4.0\times10^{-28}}$, that is $2\times10^{-14}$.

3.Q.84 The precipitation occurs if the ionic concentration is: (UHS MDCAT 2023)

  1. Less than ksp
  2. More than ksp
  3. Equal to ksp
  4. Present in any amount
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Correct answer: (b) More than ksp

A solid comes down once the ionic product exceeds the solubility product.

4.Ksp (Solubility product) depends upon: (PMC MDCAT 2022)

  1. Pressure
  2. Concentration
  3. Temperature
  4. Volume
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Correct answer: (c) Temperature

Like any equilibrium constant, the solubility product changes only with temperature.

5.Which term describes a solution in which dissolved solute is in equilibrium with undissolved solute? (NUMS MDCAT 2022)

  1. Dilute
  2. Saturated
  3. Unsaturated
  4. Supersaturated
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Correct answer: (b) Saturated

A saturated solution is one in equilibrium with the undissolved solid.

6.The product of the concentrations of each ion in a saturated solution of a sparingly soluble salt at 298 K, raised to the power of their relative concentrations is: (UHS MDCAT 2018)

  1. Ksp
  2. Ka
  3. Kw
  4. Kb
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Correct answer: (a) Ksp

That product is the solubility product, $K_{sp}$.

7.Ca(OH)2 is sparingly soluble having solubility constant value 6.5 x 10-6. What’ll be its solubility: (UHS MDCAT 2017)

  1. 2.75 x 10-2
  2. 2.75 x 102
  3. 1.17 x 10-2
  4. 3.63 x 103
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Correct answer: (c) 1.17 x 10-2

$K_{sp}=4s^3$, so $s=\sqrt[3]{6.5\times10^{-6}/4}$, about $1.17\times10^{-2}$.

8.Value of Ksp for PbSO4 system at 25 °C is equal to: (UHS MDCAT 2016)

  1. 1.6 x 10-5 mol2dm-6
  2. 1.6 x 10-6 mol2dm-6
  3. 1.6 x 10-8mol2dm-6
  4. 1.6 x 10-7 mol2dm-6
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Correct answer: (c) 1.6 x 10-8mol2dm-6

The solubility product of lead sulphate at $25^{\circ}\mathrm{C}$ is about $1.6\times10^{-8}$.

9.Which one of the following is the correct presentation for Ksp? AgCl Ag+ + Cl― [AgCl] (UHS MDCAT 2015)

  1. Ksp = [Ag +1
  2. Ksp = [Ag+1] [Cl-1] +1 -1 ] [Cl ] [AgCl]
  3. Ksp = -1 [Ag ] [Cl ]
  4. Ksp = [AgCl] ENGLISH
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Correct answer: (b) Ksp = [Ag+1] [Cl-1] +1 -1 ] [Cl ] [AgCl]

The solubility product is the product of the ionic concentrations; the solid does not appear in it.

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