Ionic Equilibrium questions

All of the following are correct, except ..........

1. A Molten potassium chloride is a strong electrolyte.
2. B Hydrogen chloride in benzene is a strong electrolyte.
3. C A solution of acetic acid in water is a weak electrolyte.
4. D A solution of ammonia in water is a weak electrolyte.

In which of the following compound solutions does ionic equilibrium not occur?

1. A CH₃COOH
2. B NH₄OH
3. C H₂CO₃
4. D KCl

Strong electrolyte solutions include ..........

1. A HCl , NH₃ , NaCl
2. B HCl , NaNO₃ , KOH
3. C HCl , NaCl , CH₃COOH
4. D HCl , NH₃ , CH₃COOH

Which of the following aqueous solutions (of equal concentration) is the poorest conductor of electricity?

1. A H₂SO₄
2. B H₂S
3. C NaOH
4. D NaNO₃

Which equation represents the ionization of HSO₃⁻ in water?

1. A HSO₃⁻ + H₂O ⇌ H₂SO₄ + H⁺
2. B HSO₃⁻ + H₂O ⇌ SO₃²⁻ + H₃O⁺
3. C HSO₃⁻ + H₂O ⇌ H₂SO₃ + OH⁻
4. D HSO₃⁻ + H₂O ⇌ H₂SO₄ + ½H₂

Which of the following represents the dissolving of acetic acid in water?

1. A CH₃COOH + H₂O → CH₃COO⁻ + OH⁻
2. B CH₃COOH + H₂O → CH₃COO⁻ + H₃O⁺
3. C CH₃COOH + H₂O ⇌ CH₃COO⁻ + H₃O⁺
4. D CH₃COOH + H₂O ⇌ CH₃COO⁻ + OH⁻

Which of the following aqueous solutions (of equal concentration) has the highest electrical conductivity?

1. A HCl
2. B H₃BO₃
3. C NH₃
4. D CH₃COOH

Which of these acids has the lowest ionization constant?

1. A HCl
2. B HBr
3. C HNO₂
4. D HNO₃

[H⁺] is the greatest in the solution made by dissolving ..........

1. A 0.3 mol of CO₂ in 200 mL of water.
2. B 0.8 mol of CH₃COOH in 200 mL of water.
3. C 1 mol of CH₃COOH in 200 mL of water.
4. D 0.2 mol of HCl in 50 mL of water.

Which of the following contains the greatest number of moles of ions?

1. A H⁺(aq) ions in 0.1 L of 0.5 M acetic acid
2. B OH⁻(aq) ions in 0.5 L of 0.1 M sodium hydroxide solution
3. C H⁺(aq) ions in 0.2 L of 0.2 M hydrochloric acid
4. D OH⁻(aq) ions in 0.4 L of 1 M ammonium hydroxide solution

All of the following describe the cation formed when hydrogen chloride gas dissolves in water, except that it ..........

1. A turns litmus red.
2. B contains a coordinate bond.
3. C has a concentration different from that of the chloride ions.
4. D is a hydrated proton.

The 0.1 M solution that contains the highest concentration of hydronium ions is ..........

1. A CH₃COOH
2. B NaCl
3. C Ba(OH)₂
4. D Na₂CO₃

The opposite table shows the time needed to obtain 30 mL of hydrogen gas from the reaction of zinc with a mineral acid in two different experiments.
Experiment (1): 25 mL of 1 M H₂SO₄ , time 28 s
Experiment (2): 25 mL of 1 M HCl , time 56 s
The time of experiment (1) is less than that of experiment (2), because ..........

1. A the acid is more stable in experiment (1).
2. B the number of moles of acid is greater in experiment (1).
3. C the number of moles of (H⁺) is greater in experiment (1).
4. D the number of moles of anions is greater in experiment (1).

In deriving Ostwald's law, the relation α = √(Ka V) expresses the degree of ionization of ..........

1. A a weak acid of volume V containing a known mass of solute.
2. B a weak base of volume V containing a known mass of solute.
3. C a weak base of volume V containing 1 mol of solute.
4. D a weak acid of volume V containing 1 mol of solute.

What happens to a weak acid when it is diluted with water?

1. A Its Ka decreases and its degree of ionization increases.
2. B Its Ka decreases and its degree of ionization decreases.
3. C Its Ka does not change and its degree of ionization increases.
4. D Its Ka does not change and its degree of ionization decreases.

From the table: Ka (at 25°C) for CH₃COOH = 1.8 × 10⁻⁵ , and for HCN = 0.2 × 10⁻¹⁰
In which of the following solutions is the degree of ionization of the solute the lowest?

1. A 0.1 M HCN solution
2. B 0.01 M HCN solution
3. C 0.01 M CH₃COOH solution
4. D 0.001 M CH₃COOH solution

An organic acid has an ionization constant of 1 × 10⁻⁵. What is its degree of ionization when its concentration is 0.1 M?

1. A 10⁻²
2. B 10⁻³
3. C 10⁻⁴
4. D 10⁻⁵

A weak monoprotic organic acid has a degree of ionization of 3.72% (at 25°C) and an ionization constant of 6.88 × 10⁻⁵
What is the molar concentration of the acid?

1. A 5 × 10⁻² M
2. B 1 × 10⁻¹ M
3. C 2 × 10⁻² M
4. D 5 × 10⁻¹ M

A basic solution has a degree of ionization of 3.873 × 10⁻⁶ when its concentration is 0.001 M
What is its ionization constant?

1. A 4.4 × 10⁻⁴
2. B 1.1 × 10⁻⁸
3. C 1.4 × 10⁻⁹
4. D 1.5 × 10⁻¹⁴

What is the degree of ionization of a 250 mL solution containing 0.5 g of hydrofluoric acid, given that the ionization constant of the acid is 6.7 × 10⁻⁴? [F = 19 , H = 1]

1. A 0.82
2. B 0.41
3. C 0.041
4. D 0.082

What is the non-ionized percentage of nitrous acid of concentration 0.5 M, volume 1 L and ionization constant 7.1 × 10⁻⁴?

1. A 1.9%
2. B 3.8%
3. C 96.2%
4. D 98.1%

If the ionization constant of benzoic acid C₆H₅COOH is 6.5 × 10⁻⁵
what is [H₃O⁺] in a solution of this acid whose concentration is 0.55 M?

1. A 3.575 × 10⁻⁴ M
2. B 3.575 × 10⁻³ M
3. C 6 × 10⁻⁴ M
4. D 6 × 10⁻³ M

The concentration of acetate ions in a 0.18 M acetic acid solution (Ka = 1.76 × 10⁻⁵) equals ..........

1. A 0.18 M
2. B 1.8 × 10⁻³ M
3. C 3.17 × 10⁻⁶ M
4. D 4.2 × 10⁻³ M

The opposite table shows the Ka values of formic acid HCOOH and acetic acid CH₃COOH, each of concentration 0.1 M
Ka of HCOOH = 1.8 × 10⁻⁴ , Ka of CH₃COOH = 1.8 × 10⁻⁵
Which of the following is present at the highest concentration?

1. A CH₃COOH in the acetic acid solution.
2. B CH₃COO⁻ in the acetic acid solution.
3. C HCOOH in the formic acid solution.
4. D HCOO⁻ in the formic acid solution.

A weak base solution has a concentration of 0.35 M and a hydroxide ion concentration of 1.5 × 10⁻⁵ M
What is the value of (Kb)?

1. A 6.16 × 10⁻³
2. B 6.43 × 10⁻¹⁰
3. C 1.5 × 10⁻⁶
4. D 4.28 × 10⁻⁴

25 mL of acid (X) of concentration 0.75 M reacts completely with 15 mL of 2.5 M NaOH solution.
Which of the following represents acid (X) and its ionization constant?

1. A Acetic acid , (Ka = 1.8 × 10⁻⁵).
2. B Sulphuric acid , (Ka = 1.8 × 10⁻⁴).
3. C Nitrous acid , (Ka = 4.5 × 10⁻⁴).
4. D Sulphurous acid , (Ka = 1.7 × 10⁻²).

If the ionization constant of a weak monoprotic acid is 7.2 × 10⁻¹⁰ and its degree of dissociation is 8.5 × 10⁻⁵
what is [H₃O⁺] in a solution of this acid?

1. A 8.47 × 10⁻⁶ M
2. B 84.7 × 10⁻⁶ M
3. C 9.9 × 10⁻³ M
4. D 0.099 × 10⁻³ M

What is the concentration of OH⁻ ions in a known volume of 0.015 M H₂SO₄?

1. A 5 × 10⁻¹² M
2. B 3.3 × 10⁻¹³ M
3. C 6.7 × 10⁻¹³ M
4. D 2 × 10⁻⁹ M

What is the concentration of H₃O⁺ ions in the solution formed by adding 60 mL of water to 40 mL of 0.04 M KOH solution?

1. A 6.25 × 10⁻⁵ M
2. B 6.25 × 10⁻⁸ M
3. C 6.25 × 10⁻¹¹ M
4. D 6.25 × 10⁻¹³ M

Kw of pure water (at 100°C) equals 51.3 × 10⁻¹⁴
Which of the following describes water at this temperature?

1. A Neutral , [H₃O⁺] = 7.16 × 10⁻⁷ M
2. B Acidic , [H₃O⁺] = 7.16 × 10⁻⁷ M
3. C Basic , [OH⁻] = 10⁻⁷ M
4. D Neutral , [OH⁻] = 10⁻⁷ M

Which of the following substances is the most acidic?

1. A Grapefruit , its pH is 3
2. B Synthetic detergent , its pH is 10.5
3. C Gastric juice , its pH is 1
4. D Sea water , its pH is 8.5

What is the pH of a 0.4 M H₃BO₃ solution whose ionization constant is 7.3 × 10⁻¹⁰?

1. A 1.7
2. B 4.77
3. C 6.12
4. D 8.22

If you have a 0.2 M weak alkaline solution whose equilibrium constant Kb is 3.6 × 10⁻⁴
then the pOH of the solution equals ..........

1. A 1.70
2. B 4.07
3. C 3.02
4. D 2.07

If the ionization constant of an HCN solution equals 4.9 × 10⁻¹⁰
then the Kb of the solution equals ..........

1. A 2 × 10⁻⁶
2. B 2 × 10⁻⁵
3. C 2 × 10⁵
4. D 2 × 10⁶

The pH of 0.1 M H₂SO₄ (at 25°C) is ..........

1. A less than 1
2. B equal to 1
3. C equal to 2
4. D equal to 3

4 g of sodium hydroxide were dissolved to form a 500 mL solution. [Na = 23 , O = 16 , H = 1]
What is the (pH) of the solution?

1. A 0.7
2. B 0.2
3. C 13.3
4. D 13.8

What is the pOH of a 0.05 M HCl solution?

1. A 0.3
2. B 1.3
3. C 12.7
4. D 13.7

What is the pH of a 0.1 M ammonia solution whose ionization constant is 4 × 10⁻⁵?

1. A 9
2. B 11.3
3. C 5
4. D 2.7

Every 100 mL of vinegar contains 5 g of acetic acid. If the molar mass of this acid is 60 g/mol and its ionization constant is 1.8 × 10⁻⁵, what is the pH of the solution?

1. A 2.41
2. B 2.92
3. C 5.85
4. D 6.73

A 0.01 M H₂CO₃ solution has a hydronium ion concentration of 6.557 × 10⁻⁵ M
What are the values of Ka and Kb for this solution?

1. A Ka : 4.3 × 10⁻⁷ , Kb : 2.3 × 10⁻⁸
2. B Ka : 4.3 × 10⁻⁷ , Kb : 0.23 × 10⁻⁵
3. C Ka : 0.23 × 10⁻⁵ , Kb : 4.3 × 10⁻⁹
4. D Ka : 2.3 × 10⁻⁸ , Kb : 4.3 × 10⁻⁷

Adding 0.01 mol of HCl to 1 L of pure water changes the pH of the pure water by ..........

1. A 0.01
2. B 2
3. C 5
4. D 7

How many H⁺ ions are there in 1 mL of a solution whose pOH is 10 (at 25°C)?

1. A 6.02 × 10¹⁰ ion
2. B 6.02 × 10¹⁶ ion
3. C 6.02 × 10¹³ ion
4. D 10¹³ ion

The opposite figure shows the distillation of a sodium hydroxide solution (A).
Which of the following gives the pH of liquid (B) produced by distillation compared with the pH of solution (A), and the concentration of solution (A) a few minutes after distillation starts, respectively?

1. A Greater , increases.
2. B Greater , decreases.
3. C Less , increases.
4. D Less , decreases.

If the solubility of the salt MnS (at 25°C) is 4.8 × 10⁻⁷ M
what is the solubility product of this salt?

1. A 2.3 × 10⁻¹³
2. B 4.8 × 10⁻⁷
3. C 9.6 × 10⁻⁷
4. D 6.9 × 10⁻¹⁴

What is the solubility product of the salt Ag₂SO₄, given that its solubility in water at a certain temperature is 1.4 × 10⁻²?

1. A 1.0976 × 10⁻⁵
2. B 10.976 × 10⁻⁵
3. C 1.96 × 10⁻⁴
4. D 19.6 × 10⁻⁴

A saturated solution of calcium phosphate has [PO₄³⁻] = 3.3 × 10⁻⁷ M
What is the Ksp of calcium phosphate?

1. A 1.32 × 10⁻³¹
2. B 1.32 × 10⁻³²
3. C 1.32 × 10⁻³³
4. D 1.32 × 10⁻³⁵

Which of the following expresses the solubility product of zinc phosphate?

1. A Ksp = [Zn²⁺] [PO₄³⁻]
2. B Ksp = [Zn²⁺]³ [PO₄³⁻]²
3. C Ksp = [Zn²⁺] [2PO₄³⁻]
4. D Ksp = [3Zn²⁺]³ [2PO₄³⁻]²

If the solubility of copper(II) iodate Cu(IO₃)₂ is 3.3 × 10⁻³ M at a certain temperature
what is its Ksp?

1. A 1.4 × 10⁻⁷
2. B 1.1 × 10⁻⁵
3. C 3.3 × 10⁻³
4. D 5.1 × 10⁻¹

The solubility of barium oxalate in water is 4.8 × 10⁻⁴ M
What is the Ksp of this salt?

1. A 2.3 × 10⁻⁷
2. B 3.9 × 10⁻⁶
3. C 2.4 × 10⁻⁴
4. D 2.2 × 10⁻²

If [Ba²⁺] in a saturated solution of BaF₂ is 3.6 × 10⁻³ M
what is the Ksp of this salt?

1. A 12.96 × 10⁻⁶
2. B 1.86 × 10⁻⁷
3. C 12.96 × 10⁻⁷
4. D 1.86 × 10⁻⁶

What is [X⁺] in a saturated solution of the salt (XY) if Ksp = 1.8 × 10⁻¹⁰?

1. A 13.4 × 10⁻⁶ M
2. B 13.4 × 10⁻³ M
3. C 26.8 × 10⁻⁷ M
4. D 18 × 10⁻⁵ M

The salt AgBrO₃ has a solubility product of 5.5 × 10⁻⁵
What is the solubility of this salt?

1. A 2.8 × 10⁻⁹ M
2. B 5.3 × 10⁻⁵ M
3. C 1.1 × 10⁻⁴ M
4. D 7.4 × 10⁻³ M

The solubility product of SrF₂ is 4.3 × 10⁻⁹, so its solubility is ..........

1. A 3.2 × 10⁻²⁵ M
2. B 1.8 × 10⁻¹⁷ M
3. C 4.3 × 10⁻⁹ M
4. D 1 × 10⁻³ M

If the solubility product of A₂B₃ is 1.08 × 10⁻²³, then its solubility equals ..........

1. A 1 × 10⁻³ M
2. B 1 × 10⁻⁴ M
3. C 1 × 10⁻⁵ M
4. D 1 × 10⁻⁶ M

From the opposite table: Ksp of the solutions: ZnS = 2 × 10⁻²⁵ , CuS = 6 × 10⁻³⁷ , PbS = 2.5 × 10⁻²⁷ , CoS = 4 × 10⁻²¹
Which of the following saturated solutions contains the lowest concentration of S²⁻ ions?

1. A ZnS
2. B CuS
3. C PbS
4. D CoS

What is the concentration of OH⁻ ions in a saturated solution of Mg(OH)₂? [Ksp (Mg(OH)₂) = 5.6 × 10⁻¹²]

1. A 1.1 × 10⁻⁴ M
2. B 2.2 × 10⁻⁴ M
3. C 1.4 × 10⁻¹² M
4. D 2.8 × 10⁻⁶ M

If the solubility of Pb(OH)₂ is 0.0155 g/100 g H₂O [Pb = 207 , O = 16 , H = 1]
what are the concentrations of the two ions of this compound in its saturated solution?

1. A [Pb²⁺] : 0.155 g/L , [OH⁻] : 0.155 g/L
2. B [Pb²⁺] : 0.052 g/L , [OH⁻] : 0.103 g/L
3. C [Pb²⁺] : 6.43 × 10⁻⁴ M , [OH⁻] : 1.29 × 10⁻³ M
4. D [Pb²⁺] : 6.43 × 10⁻⁴ M , [OH⁻] : 6.43 × 10⁻³ M

A magnesium hydroxide solution has a pH of 10.45, so its solubility product is ..........

1. A 2.24 × 10⁻⁴
2. B 1.12 × 10⁻¹¹
3. C 3.36 × 10⁻¹¹
4. D 5.6 × 10⁻¹²

25 mL of 0.15 M AgNO₃ solution was added to 15 mL of 0.2 M NaCl solution. [Ksp (AgCl) = 1.8 × 10⁻¹⁰]
Which of the following is correct?

1. A A precipitate forms, because [Ag⁺] [Cl⁻] > Ksp
2. B No precipitate forms, because [Ag⁺] [Cl⁻] < Ksp
3. C A precipitate forms, because [Ag⁺] [Cl⁻] < Ksp
4. D No precipitate forms, because [Ag⁺] [Cl⁻] > Ksp

On evaporating 200 mL of a saturated solution of the salt SrCrO₄, 1.2 × 10⁻³ mol of the dry salt was obtained.
What is the solubility of this salt?

1. A 1.4 × 10⁻⁶ M
2. B 3.6 × 10⁻⁵ M
3. C 2.4 × 10⁻⁴ M
4. D 6 × 10⁻³ M

What is the lowest [CO₃²⁻] that must be added to a 1.3 × 10⁻⁴ M AgNO₃ solution for a precipitate to form? [Ksp (Ag₂CO₃) = 8.5 × 10⁻¹²]

1. A 5 × 10⁻⁴ M
2. B 6.5 × 10⁻¹⁰ M
3. C 5 × 10⁻¹⁰ M
4. D 6.5 × 10⁻⁴ M

From the opposite table: Ksp of the salts AgBr = 5.4 × 10⁻¹³ , Bi₂S₃ = 2 × 10⁻⁷⁸ , CuS = 6 × 10⁻³⁷
Which of the following gives the correct order of the solubility of the salts in water (at 25°C)?

1. A CuS < Bi₂S₃ < AgBr
2. B AgBr < CuS < Bi₂S₃
3. C Bi₂S₃ < CuS < AgBr
4. D AgBr < Bi₂S₃ < CuS

The following equation represents the equilibrium in a saturated solution of barium sulphate: BaSO₄(s) ⇌ Ba²⁺(aq) + SO₄²⁻(aq)
When the salt Na₂SO₄ is added to the saturated solution, the system shifts in the ..........

1. A backward direction and [Ba²⁺] decreases.
2. B backward direction and [Ba²⁺] increases.
3. C forward direction and [Ba²⁺] decreases.
4. D forward direction and [Ba²⁺] increases.

A mixture is made of three solutions of equal volume and concentration of:
• sulphuric acid. • sodium hydroxide. • potassium hydroxide.
Predict the pH of the resulting mixture, with explanation.

Phosphoric acid ionizes in three successive steps:
(1) Write the expression of the ionization constant Ka for the first step.
(2) Do you expect Ka to be (6.9 × 10⁻³) or (1.7 × 10⁵)? Explain.

What is the effect of adding drops of NaOH to distilled water on:
(1) the concentration of hydronium ions?
(2) the pH value?

The opposite table shows the Kb values of three weak bases: (A) : 1.4 × 10⁻⁹ , (B) : 4.7 × 10⁻⁴ , (C) : 1.1 × 10⁻⁸
Arrange the solutions of these bases (of equal concentration) in ascending order of their pH.

What type of solution is solution (X), whose H₃O⁺ concentration is 2 × 10⁻³ M? Explain.

Hydrochloric acid reacts with substance (X) to form a solution that gives a green colour with bromothymol blue indicator:
(1) Suggest the name of substance (X), with explanation.
(2) What is the pOH of the resulting solution?

Arrange the following solutions of equal concentration (0.1 M) in ascending order of pH, with explanation:
(HCl , NaOH , H₃BO₃ , NH₄OH)

The pH of an aqueous solution is affected when its temperature rises above 25°C
State two other factors that affect the pH of acids.

The following table shows the pH values of several solutions of equal concentration:
pH of solution (A) = 11 , (B) = 3 , (C) = 7 , (D) = 5 , (E) = 13 , (F) = 9 , (G) = 1
Give the symbol of:
(1) the weakest acid, with explanation.
(2) the best conductor of electricity among solutions (B), (F) and (G), with explanation.

Does axis (X) in the opposite graph represent pOH or pH? Explain.

100 mL of distilled water was added to 100 mL of hydrochloric acid whose pH is 3
Calculate the pH of the acid after dilution.

Calculate [OH⁻] and pOH for benzoic acid, given that its concentration is 0.2 M and its ionization constant Ka equals 6.5 × 10⁻⁵

The following table shows the pH values of several solutions of equal concentration:
pH of solution (A) = 11 , (B) = 3 , (C) = 7 , (D) = 5 , (E) = 13 , (F) = 9 , (G) = 1
Give the symbol of the solution that:
(1) has the highest OH⁻ concentration, with explanation.
(2) may be a sodium chloride solution.

Potassium sulphide solution reacts with cobalt(II) acetate solution, forming two salts, one of which is sparingly soluble in water.
Write the chemical formula of the salt produced that:
(1) has the greater solubility in water.
(2) has a Ksp value.

Two saturated solutions of Ag₂CO₃ and AgCl at 25°C
Show by chemical calculations which of these two solutions contains the higher [Ag⁺], given that:
• the solubility product of silver chloride is 1.8 × 10⁻¹⁰
• the solubility product of silver carbonate is 8.5 × 10⁻¹²

The following figures show three solutions (A , B , C) of hydrofluoric acid at room temperature: solution (A): M = 0.4 M , Ka = 6.7 × 10⁻⁴ , solution (B): M = 0.28 M , solution (C): M = 0.02 M
Study the figures, then answer:
(1) Which solution has the highest pH?
(2) Which solution has the highest concentration of negative fluoride ions?
(3) What is the Ka value of solution (B)?
(4) In which solution is the percentage dissociation of the acid 4.9 %?

A basic dihydroxide compound is sparingly soluble in water. If the pH of this compound is 8, deduce its Ksp.

50 mL of 0.2 M ammonium hydroxide (NH₄OH) solution was diluted by adding 450 mL of distilled water.
What is the degree of dissociation (α) of the solution after dilution? (Ionization constant of ammonia solution: Kb = 1.8 × 10⁻⁵)

1. A 0.03
2. B 0.0095
3. C 0.2
4. D 0.0009

Two test tubes (A) and (B) each contain a saturated solution of calcium carbonate: CaCO₃(s) ⇌ Ca²⁺(aq) + CO₃²⁻(aq)
• In tube (A): a few drops of hydrochloric acid were added.
• In tube (B): a few drops of calcium chloride solution were added.
Which of the following is correct?

1. A The amount of precipitate gradually increases in (A), and gradually decreases in (B).
2. B The amount of precipitate gradually decreases in (A), and gradually increases in (B).
3. C The amount of precipitate gradually increases in both tubes.
4. D The amount of precipitate gradually decreases in both tubes.

Drops of solution (X) were added to some distilled water, and the pOH of the water was observed to decrease.
Which of the following represents solution (X)?

1. A A base , its pOH is 8
2. B An acid , its pOH is 5
3. C A base , its pH is 8
4. D An acid , its pH is 5

A 5 L saturated solution of zinc sulphide (ZnS) was cooled from 60°C to 25°C, and a mass of 1.53 × 10⁻⁵ g of the salt precipitated.
Given that the solubility product Ksp of the salt at 25°C equals 1 × 10⁻²¹ [ZnS = 97 g/mol]
which of the following represents the solubility product (Ksp) of ZnS at 60°C?

1. A 1 × 10⁻¹⁵
2. B 1 × 10⁻²¹
3. C 3.16 × 10⁻⁸
4. D 3.16 × 10⁻¹¹

A hydrocyanic acid solution is in equilibrium according to the following equation: HCN + H₂O(l) ⇌ H₃O⁺(aq) + CN⁻(aq)
Which of the following happens when a few drops of HCl are added to this solution?

1. A The degree of dissociation of the acid increases.
2. B The concentration of the CN⁻ ion increases.
3. C The degree of dissociation of the acid decreases.
4. D The equilibrium is not affected.

Solution (X) has a hydrogen ion concentration [H⁺] of 1.0 × 10⁻⁹ M at 25°C
Which of the following represents solution (X)?

1. A A solution of a base whose pOH is 9
2. B A solution of an acid whose pOH is 5
3. C A solution of a base whose pH is 9
4. D A solution of an acid whose pH is 5

From the figure in front of you, every 50 mL of the solution was found to contain 2 × 10⁻⁴ mol of solute.
Which of the following represents the Ksp of the salt Mg(OH)₂?

1. A 4 × 10⁻⁶
2. B 2.5 × 10⁻⁷
3. C 1.6 × 10⁻⁸
4. D 8 × 10⁻⁵

All of the following solutions have a degree of dissociation (α ≃ 1), except ..............

1. A hydrochloric acid (1 M).
2. B sodium hydroxide (1 M).
3. C nitric acid (1 M).
4. D boric acid (1 M).

An acetic acid solution ionizes according to the following equation: CH₃COOH ⇌ H⁺ + CH₃COO⁻
Which of the following happens when drops of sodium hydroxide are added to this solution?

1. A The dissociation of the acid increases and the pH of the solution decreases.
2. B The dissociation of the acid increases and the pH of the solution increases.
3. C The rate of forming the acid increases and the pH of the solution decreases.
4. D The rate of forming the acid increases and the pH of the solution increases.

An ammonium hydroxide (NH₄OH) solution of concentration 0.1 M at 25°C has an equilibrium constant Kb = 1.8 × 10⁻⁵
Which of the following is correct?

1. A α = 0.0134 , pOH = 11.13 , pH = 2.87
2. B α = 0.0134 , pOH = 2.87 , pH = 11.13
3. C α = 1 , pOH = 1 , pH = 13
4. D α = 1.8 × 10⁻⁵ , pOH = 4.74 , pH = 9.26

Which of the following choices does not represent an equilibrium system?

1. A Dissolving ammonia gas in water.
2. B A reversible reaction with constant concentrations.
3. C Strong heating of hydrated barium chloride.
4. D A saturated solution of a sparingly soluble salt.

Two solutions (A , B) have the same volume and concentration:
• (A): a weak acid solution (such as CH₃COOH).
• (B): a weak base solution (such as NH₄OH).
On diluting each solution by adding 100 mL of distilled water, which of the following describes what happens after dilution?

1. A The pH decreases in both solutions (A) and (B).
2. B The pH of solution (A) increases and the pH of solution (B) decreases.
3. C The pH increases in both solutions (A) and (B).
4. D The pH of solution (A) decreases and the pH of solution (B) increases.

A 500 mL sodium hydroxide NaOH solution has a pH of 12.0 [Na = 23 , O = 16 , H = 1]
so the mass of sodium hydroxide (NaOH) dissolved in this solution equals ..............

1. A 2.0 g
2. B 0.2 g
3. C 0.4 g
4. D 4.0 g

Four saturated solutions of sparingly soluble salts at 25°C:
(1) AgCl , Ksp = 1.0 × 10⁻¹⁰ , (2) PbI₂ , Ksp = 4.0 × 10⁻¹²
(3) AgBr , Ksp = 1.0 × 10⁻⁸ , (4) BiI₃ , Ksp = 2.7 × 10⁻¹⁵
Which of the following gives the order of these solutions according to their electrical conductivity?

1. A 4 > 3 > 2 > 1
2. B 4 > 2 > 3 > 1
3. C 3 > 1 > 2 > 4
4. D 1 > 3 > 2 > 4

Two solutions of two different acids, both weak, (HA) and (HB), each with pH = 3.
• The acid HA has a concentration of 0.1 M
• The acid HB has a concentration of 0.01 M
Which of the following is correct for the two acids HA and HB?

1. A They differ in the concentration of the OH⁻ ion
2. B They have the same Ka
3. C The Ka of HB is greater.
4. D The Ka of HA is greater.

Four solutions of the same concentration: (1) HCl solution , (2) NaOH solution , (3) CH₃COOH solution , (4) NH₄OH solution
Which of the following gives the correct order of these solutions according to the concentration of the hydronium ion?

1. A 2 < 4 < 3 < 1
2. B 1 < 3 < 4 < 2
3. C 4 < 3 < 2 < 1
4. D 4 < 2 < 3 < 1

Given that the solubility product of lead(II) chloride, which is sparingly soluble in water, is (Ksp = 1.2 × 10⁻⁵) at 25°C [PbCl₂ = 278 g/mol]
which of the following represents the volume of saturated solution that contains 0.1 g of the salt at the same temperature?

1. A 25 mL
2. B 50 mL
3. C 100 mL
4. D 150 mL

A saturated solution of lead(II) chloride (PbCl₂) is in equilibrium according to the following equation: PbCl₂(s) ⇌ Pb²⁺(aq) + 2Cl⁻(aq)
Which of the following is correct for the solubility of PbCl₂ when a little of each of the following salts is added separately?

1. A The solubility decreases on adding sodium sulphate solution.
2. B The solubility increases on adding sodium nitrate solution.
3. C The solubility decreases on adding lead(II) acetate solution.
4. D The solubility increases on adding potassium nitrate solution.

Each of the following can represent an equilibrium system, except ..............

1. A A saturated solution of a sparingly soluble salt in water.
2. B Dissolving carbon dioxide in water in a closed container.
3. C Dissolving acetic acid in water in an open container.
4. D Obtaining oxygen gas by decomposing H₂O₂

The following table shows the pH of three solutions of different acids that have the same concentration:
Solution A : pH = 1 , solution B : pH = 6 , solution C : pH = 3
The correct order of these solutions according to their acid ionization constant Ka is ..............

1. A B > A > C
2. B A > B > C
3. C C > B > A
4. D A > C > B

A 0.1 M acetic acid solution (X) was diluted by adding water to obtain solution (Y) of concentration 0.01 M
Which of the following does not describe the two solutions (X , Y)?

1. A The electrical conductivity of solution (Y) is higher than that of (X).
2. B The concentration of hydronium ions in solution (X) is higher than in (Y).
3. C The pH of solution (Y) is higher than that of solution (X).
4. D The ionization constant of the acid in solution (X) is higher than in (Y).

If the solubility of magnesium carbonate MgCO₃ in water at 25°C is [4.4 × 10⁻⁵ mol/100 mL H₂O]
then the solubility product (Ksp) of this salt equals ..............

1. A 4.16 × 10⁻¹¹
2. B 1.9 × 10⁻⁷
3. C 19.36 × 10⁻¹⁰
4. D 6.44 × 10⁻⁴

A hydrocyanic acid (HCN) solution has a pH of 4.7 and an acid ionization constant (Ka = 6.2 × 10⁻¹⁰)
so the number of moles of acid dissolved in 300 mL of its solution equals ..............

1. A 0.19
2. B 0.47
3. C 0.64
4. D 0.14

The ionic product of water (Kw) increases as the temperature increases.
Which of the following happens when the temperature of water is raised?

1. A The concentration of hydrogen ions increases, the pH of water increases and it becomes acidic to litmus solution.
2. B The concentration of hydroxide ions increases, the pOH of water decreases and it becomes alkaline to litmus solution.
3. C The concentration of hydroxide ions increases, the pOH of water decreases and it stays neutral to litmus solution.
4. D The concentration of hydrogen ions increases, the pH of water increases and it stays neutral to litmus solution.

A saturated solution of a sparingly soluble salt (A) has a concentration of 1 × 10⁻⁴ mol/L. Given that the solubility product of this salt equals 1.08 × 10⁻¹⁸
which of the following represents the chemical formula of salt (A)?

1. A X₂Y₃
2. B XY₃
3. C X₂Y
4. D XY₂

Two solutions of two different acids (X) and (Y), each monoprotic:
• (X): concentration 0.1 M and ionization constant Ka = 1.8 × 10⁻⁵
• (Y): concentration 0.1 M and ionization constant Ka = 5.1 × 10⁻⁴
Which of the following describes the properties of acids (X) and (Y)?

1. A The solution of acid (X) conducts electricity better and its pH is lower than that of acid (Y).
2. B The solution of acid (Y) conducts electricity better and its pH is higher than that of acid (X).
3. C The solution of acid (X) conducts electricity less and its pH is lower than that of acid (Y).
4. D The solution of acid (Y) conducts electricity better and its pH is lower than that of acid (X).

If the Ksp of the salt AgCl equals 1.6 × 10⁻¹⁰
then the concentration of dissolved ions in its saturated solution equals ..............

1. A 1.26 × 10⁻⁵ M
2. B 2.53 × 10⁻⁵ M
3. C 6.32 × 10⁻⁶ M
4. D 1.6 × 10⁻¹⁰ M

Which of the following represents the mass of Ba(OH)₂ dissolved in 1.5 L of pure water needed to form a solution of pH 12.3? [Ba(OH)₂ = 171 g/mol]

1. A 2.56 g
2. B 5.12 g
3. C 43.605 g
4. D 0.513 g

0.2 mol of hydrocyanic acid was dissolved in a litre of water, and the concentration of the non-ionized acid in the water was 0.167 M,
so the ionization constant of the acid at the same temperature equals ..............

1. A 4.18 × 10⁻³
2. B 5.45 × 10⁻³
3. C 3.03 × 10⁻³
4. D 6.06 × 10⁻³

A weak monoprotic acid solution is diluted by adding water so that its volume doubles.
Which of the following happens to the values of pH and α?

1. A Its value decreases and becomes (α / 1.414), and the pH of the solution decreases.
2. B Its value increases and becomes (1.414 α), and the pH of the solution increases.
3. C α doubles, and the pH of the solution increases.
4. D α is halved, and the pH of the solution decreases.

If the Ksp of the salt AgCl equals 1.6 × 10⁻¹⁰, then the mass of salt dissolved in 50 mL of water equals .............. [AgCl = 143.5 g/mol]

1. A 1.6 × 10⁻¹⁰ g
2. B 0.905 × 10⁻⁴ g
3. C 1.26 × 10⁻⁵ g
4. D 1.81 × 10⁻⁴ g

A weak acid whose degree of ionization is 0.03 % and concentration is 0.2 M has a pOH of ..............

1. A 2.22
2. B 11.78
3. C 9.78
4. D 4.22

A litre of 0.1 M nitrous acid in which the number of non-ionized moles is 0.0933 mol
Which of the following represents the ionization constant of the acid?

1. A 4.5 × 10⁻⁵
2. B 4.5 × 10⁻⁴
3. C 6.7 × 10⁻³
4. D 8.7 × 10⁻²

When drops of sodium hydroxide solution are added to the following equilibrium reaction: H₂SO₃(aq) + H₂O(l) ⇌ H₃O⁺(aq) + HSO₃⁻(aq)
which of the following choices is correct?

1. A The dissociation of the acid increases and the pH of the solution increases.
2. B The dissociation of the acid decreases and the pH of the solution increases.
3. C The dissociation of the acid increases and the pH of the solution decreases.
4. D The dissociation of the acid decreases and the pH of the solution decreases.

If (Ksp = 8.75 × 10⁻¹¹) for the salt X₂Y at 25°C [X₂Y = 248 g/mol]
which of the following represents the mass of salt dissolved in 100 mL of its saturated solution at the same temperature?

1. A 0.003 g
2. B 0.007 g
3. C 0.005 g
4. D 0.009 g

From the following equations:
(1) CH₃COOH(aq) ⇌ CH₃COO⁻(aq) + H⁺(aq) (2) HNO₃(aq) → H⁺(aq) + NO₃⁻(aq)
(3) HCl(aq) → H⁺(aq) + Cl⁻(aq) (4) H₂CO₃(aq) ⇌ 2H⁺(aq) + CO₃²⁻(aq)
Which of the following choices gives the numbers of the equations that involve an ionic equilibrium?

1. A (1) , (4)
2. B (1) , (2)
3. C (1) , (2) , (3)
4. D (2) , (3) , (4)

Which of the following choices represents the result of dividing the pH of a sodium carbonate solution by the pH of a potassium chloride solution?

1. A Greater than one.
2. B Equal to 7
3. C Equal to one.
4. D Less than one.

When drops of an acid are added to pure water,
which of the following choices is correct?

1. A The concentration of the positive hydrogen ion increases and Kw increases
2. B The pOH increases and Kw stays constant.
3. C The concentration of the negative hydroxide ion decreases and Kw increases
4. D The pH increases and Kw stays constant.

A saturated solution of the substance X(OH)₂ has a pOH of 4, so its solubility product equals ..............

1. A 5 × 10⁻⁵
2. B 5 × 10⁻¹³
3. C 1 × 10⁻⁴
4. D 4 × 10⁻¹²

When drops of HCl are added to the following equilibrium reaction: HCN(aq) + H₂O(l) ⇌ H₃O⁺(aq) + CN⁻(aq)
which of the following is correct?

1. A The ionization constant of HCN increases and the concentration of the cyanide ion in the solution decreases.
2. B The ionization constant of HCN does not change and the concentration of the cyanide ion in the solution decreases.
3. C The degree of dissociation of HCN increases and the pOH of the solution increases.
4. D The degree of dissociation of HCN does not change and the pH of the solution increases.

The aqueous solution of sulphurous acid contains ..............

1. A OH⁻, HSO₃⁻, SO₃²⁻, H₃O⁺, H₂SO₃
2. B OH⁻, H₃O⁺, H₂SO₃
3. C OH⁻, HSO₃⁻, H₃O⁺
4. D OH⁻, HSO₃⁻, SO₃, H₃O⁺, H₂SO₃

The law of mass action can be applied to each of the following, except ..............

1. A H₂SO₃(aq)
2. B HCl(aq)
3. C HF(aq)
4. D H₂CO₃(aq)

In the opposite figure: tube (A) contains an aqueous solution of a weak acid, and tube (B) contains an aqueous solution of a strong acid.
Which of the following represents the change in the degree of ionization (α) after adding an equal amount of water to each tube?

1. A Tube (A): increases / tube (B): not affected
2. B Tube (A): not affected / tube (B): decreases
3. C Tube (A): decreases / tube (B): increases
4. D Tube (A): increases / tube (B): decreases

When a weak electrolyte is diluted at constant temperature, ..............

1. A the degree of ionization decreases, and the concentration of the solution increases.
2. B the degree of ionization increases, and the concentration of the solution increases.
3. C the degree of ionization increases, and the concentration of the solution decreases.
4. D the degree of ionization decreases, and the concentration of the solution decreases.

The following table shows the ionization constants of some acids:
(A) : 1.7 × 10⁻³ (B) : 1.8 × 10⁻⁵ (C) : 4.4 × 10⁻⁷ (D) : 1.2 × 10⁻²
Which of the following is correct?

1. A (B) is weaker than (C), and stronger than (A).
2. B (C) is weaker than (B), and stronger than (D).
3. C (D) is stronger than (C) and (B).
4. D (A) is stronger than (B) and (D).

7.258 g of HCN was dissolved in water and the volume of the solution became 100 mL. Given that [H = 1 , C = 12 , N = 14] , (Ka = 7.2 × 10⁻¹⁰)
the degree of ionization of the acid equals ..........

1. A 2.56 × 10⁻⁴
2. B 1.63 × 10⁻³
3. C 2.56 × 10⁻⁶
4. D 1.63 × 10⁻⁵

Given that the ionization constant (Ka) of a weak monoprotic acid equals (5.1 × 10⁻⁴) and its concentration is (0.2 M) in a solution of volume (200 mL), the number of dissociated moles equals ..........

1. A 0.04 × 10⁻² mol
2. B 1.01 × 10⁻³ mol
3. C 5.05 × 10⁻² mol
4. D 2.02 × 10⁻³ mol

In the following equilibrium system: CH₃COOH(l) + H₂O(l) ⇌ CH₃COO⁻(aq) + H₃O⁺(aq) , (Ka = 1.8 × 10⁻⁵)
when drops of HCl(aq) are added to the reaction, the Ka of acetic acid equals ..........

1. A 1.8 × 10⁻⁵
2. B 0.9 × 10⁻⁵
3. C 3.6 × 10⁻⁶
4. D 3.6 × 10⁻⁴

Given that the ionic product of water changes with temperature, and under certain temperature conditions Kw was found to be 0.49 × 10⁻¹³
the pOH of water in this case is ............

1. A 5.65
2. B 7
3. C 7.13
4. D 6.65

Two solutions (A) and (B) have pH values of [A = 8.2 , B = 13.6]
Which of the following statements is correct when each of them is diluted separately?

1. A The degree of ionization of solution (A) increases and its pH decreases.
2. B The degree of ionization of solution (A) decreases and [H⁺] decreases
3. C The degree of ionization of solution (B) decreases and its pH does not change.
4. D The degree of ionization of solution (B) increases and its pH increases.

A solution whose pOH equals 11 was added to two indicators (X) and (Y), each separately, and the following was observed:
• (X): colourless.
• (Y): red.
The two indicators (X) and (Y) are ..........

1. A (X): phenolphthalein , (Y): methyl orange.
2. B (X): phenolphthalein , (Y): bromothymol blue.
3. C (X): methyl orange , (Y): litmus.
4. D (X): litmus , (Y): bromothymol blue.

An aqueous solution of potassium chloride differs from an aqueous solution of sodium carbonate of the same concentration and volume in that ..........

1. A [OH⁻] in the potassium chloride solution is greater.
2. B the pH of the sodium carbonate solution is lower.
3. C the pH of the potassium chloride solution is lower.
4. D [H₃O⁺] in the sodium carbonate solution is greater.

The pH of a salt solution is greater than 7, so the anion and cation of this salt are ..........

1. A Anion: NO₃⁻ , cation: Na⁺
2. B Anion: SO₄²⁻ , cation: Na⁺
3. C Anion: Cl⁻ , cation: K⁺
4. D Anion: CO₃²⁻ , cation: K⁺

A monoprotic acid solution contains 0.2 mol in a volume (V) L. If Ka = 3.5 × 10⁻⁸ and the number of dissociated moles in it is 0.002 mol
then the pH of the acid equals ..........

1. A 3.5 × 10⁻⁶
2. B 5.455
3. C 8.544
4. D 6.5 × 10⁻⁷

11 g of the acid C₅H₁₁COOH was dissolved in some water until the volume of the solution became 1 L. Given that the pH of this solution at 25°C is 2.94 [H = 1 , C = 12 , O = 16]
the ionization constant of this acid equals ..........

1. A 1.39 × 10⁻⁵
2. B 1.148 × 10⁻³
3. C 1.318 × 10⁻⁶
4. D 1.39 × 10⁻⁴

Given that the concentration of a methylamine CH₃NH₂ solution is (0.4 M) and its pH = 9, its Kb at 25°C equals ..........

1. A 2.5 × 10⁻¹⁸
2. B 2 × 10⁻⁹
3. C 4.47 × 10⁻⁵
4. D 2.5 × 10⁻¹⁰

If the pOH of a weak acid equals 10 and its ionization constant equals 5.1 × 10⁻⁴, then the degree of ionization of this acid equals ..........

1. A 6.3
2. B 4.8
3. C 7.2
4. D 5.1

If the pH of an aqueous solution equals 3.7, then the hydroxide ion concentration [OH⁻] of this solution is ..........

1. A 1.99 × 10⁻⁴ M
2. B 10.3 M
3. C 5.01 × 10⁻¹¹ M
4. D 7.3 M

When 300 mL of water is added to 200 mL of NaOH solution whose pH = 12, which of the following is correct?

1. A [H⁺] increases and its pH becomes 11.6
2. B [H⁺] increases and its pH becomes 10.6
3. C [OH⁻] decreases and its pOH becomes 3.4
4. D [OH⁻] decreases and its pOH becomes 4.4

Which of the following systems is irreversible?

1. A CH₃COOH(aq) + H₂O(l) = CH₃COO⁻(aq) + H₃O⁺(aq)
2. B AgCl(s) = Ag⁺(aq) + Cl⁻(aq) (saturated solution)
3. C N₂O₄(g) = 2NO₂(g) (closed container)
4. D Zn(s) + 2HCl(aq) = ZnCl₂(aq) + H₂(g)

When HCl is added to the equilibrium system represented by the equation: AgCl(s) ⇌ Ag⁺(aq) + Cl⁻(aq)
the change that happens is ..........

1. A The concentration of Ag⁺ increases and the amount of AgCl(s) decreases
2. B Kc increases
3. C Kc decreases
4. D The concentration of Ag⁺ decreases and the amount of AgCl(s) increases

In the opposite saturated solution: AgCl(s) ⇌ Ag⁺(aq) + Cl⁻(aq)
Each of the following lowers the solubility of AgCl when added to it, except ..........

1. A NH₄OH(aq)
2. B AgNO₃(aq)
3. C NaCl(aq)
4. D HCl(aq)

The opposite equation represents a system in equilibrium: AgCl(s) ⇌ Ag⁺(aq) + Cl⁻(aq)
Which of the following changes happens when drops of lead acetate are added to this system?

1. A The rate of the backward reaction increases and the concentration of the silver ion increases.
2. B The rate of the backward reaction decreases and the concentration of the silver ion decreases.
3. C The rate of the forward reaction increases and the concentration of the chloride ion decreases.
4. D The rate of the forward reaction decreases and the concentration of the chloride ion increases.

In the opposite equilibrium: PbBr₂(s) ⇌ Pb²⁺(aq) + 2Br⁻(aq)
Which of the following choices gives the two compounds whose addition lowers the solubility of PbBr₂?

1. A NaBr, Pb(NO₃)₂
2. B Pb(NO₃)₂, NaNO₃
3. C NaBr, K₂SO₄
4. D Pb(NO₃)₂, K₂SO₄

Given that the solubility of silver chromate (Ag₂CrO₄) equals 6.62 × 10⁻⁵ M, its solubility product equals ..........

1. A 0.58 × 10⁻¹²
2. B 1.16 × 10⁻¹²
3. C 2.32 × 10⁻¹²
4. D 3.48 × 10⁻¹²

Given that the solubility product of lead hydroxide Pb(OH)₂ is 2.5 × 10⁻⁶, its solubility equals ..........

1. A 0.27 M
2. B 0.0135 M
3. C 4.27 × 10⁻³ M
4. D 8.54 × 10⁻³ M

If the solubility product of the salt XY₂ equals 1.6 × 10⁻¹⁰, then [Y⁻] equals ..........

1. A 3.41 × 10⁻⁴ M
2. B 6.84 × 10⁻⁴ M
3. C 2.36 × 10⁻⁵ M
4. D 2.14 × 10⁻⁵ M

Given that the Ksp of the salt XY₂ is 1.6 × 10⁻¹⁰, the number of moles of salt that must be dissolved in water to make 2 L of saturated solution at 25°C equals ..........

1. A 5.2 × 10⁻⁵ mol
2. B 6.84 × 10⁻⁴ mol
3. C 2.5 × 10⁻⁵ mol
4. D 3.42 × 10⁻⁴ mol

Given that the solubility product of zinc sulphide is Ksp = 1 × 10⁻²¹ and its molar mass is 97 g/mol at 25°C, the mass of zinc sulphide that dissolves in 100 g of pure water is ..........

1. A 6.034 × 10⁻¹⁰ g
2. B 31.6 × 10⁻¹² g
3. C 2 × 10⁻²¹ g
4. D 3.067 × 10⁻¹⁰ g

Given that the solubility product of silver chloride in a 0.1 L saturated solution at a certain temperature equals 2.56 × 10⁻⁶, the mass of silver chloride dissolved in the solution equals .......... [Ag = 108 , Cl = 35.5]

1. A 0.023 g
2. B 0.0115 g
3. C 2.3 × 10⁻⁶ g
4. D 1.15 × 10⁻⁶ g

A 5 L solution of zinc sulphide ZnS, which is sparingly soluble in water, has a solubility product of 1 × 10⁻¹⁵ at 60°C. On cooling to 25°C its solubility product became 1 × 10⁻²¹ [Given: ZnS = 97 g/mol]
The mass of zinc sulphide that precipitates equals ..........

1. A 1.53 × 10⁻⁵ g
2. B 3.16 × 10⁻¹¹ g
3. C 1.53 × 10⁻⁸ g
4. D 3.16 × 10⁻⁸ g