Quantitative Chemical Analysis questions

What is the number of moles in 26.5 g of sodium carbonate?
[Na = 23 , C = 12 , O = 16]

1. A 0.1 mol
2. B 0.5 mol
3. C 0.25 mol
4. D 0.125 mol

What is the number of atoms in 1 mol of hydrogen gas?

1. A 1 atom
2. B 6.02 × 10²³ atom
3. C 2 atom
4. D 12.04 × 10²³ atom

What is the volume of 16 g of oxygen gas (at STP)?
[O = 16]

1. A 22.4 L
2. B 44.8 L
3. C 11.2 L
4. D 5.6 L

What is the atomic mass of an active gas whose density is 3.1696 g/L (at STP)?

1. A 71 g/mol
2. B 35.5 g/mol
3. C 106.5 g/mol
4. D 170 g/mol

Hot conc. sulphuric acid was added to 0.05 mol of a chloride salt (X), and 6.02 × 10²² molecules of hydrogen chloride gas were given off. Which of the following represents salt (X)?

1. A NaCl
2. B BaCl₂
3. C AlCl₃
4. D TiCl₄

What is the number of water molecules produced from the reaction of 0.1 mol of hydrochloric acid with excess sodium hydroxide?

1. A 0.1 molecule
2. B 6.02 × 10²² molecule
3. C 6.02 × 10²³ molecule
4. D 6.02 × 10²⁴ molecule

When 0.02 L of NO gas is mixed with 0.01 L of O₂ gas,
what is the volume of the gas produced (at STP) after the reaction ends?

1. A 0.05 L
2. B 0.03 L
3. C 0.02 L
4. D 0.01 L

From the opposite reaction: 3Mg(s) + N₂(g) → Mg₃N₂(s) (on heating)
What is the number of moles of nitrogen gas needed to react with 18 g of magnesium?
[Mg = 24]

1. A 0.25 mol
2. B 0.5 mol
3. C 1 mol
4. D 2 mol

An aqueous solution of volume 500 mL contains 0.5 mol of CuSO₄. The concentration of this solution equals ..........

1. A 0.25 M
2. B 1 M
3. C 0.5 M
4. D 2 M

What is the concentration of the solution formed by adding 9 L of water to 1 L of 5 M H₂SO₄ solution?

1. A 0.1 M
2. B 0.5 M
3. C 1 M
4. D 5 M

What is the concentration of the nitric acid produced by adding 200 mL of water to 40 mL of 0.2 M nitric acid?

1. A 0.033 M
2. B 0.08 M
3. C 0.1 M
4. D 0.15 M

A 0.5 M caustic soda solution of volume 200 mL was diluted with water until it became 0.25 M.
What is the total volume of the resulting solution?

1. A 400 mL
2. B 300 mL
3. C 350 mL
4. D 250 mL

What volume of water must be added to 20 mL of 3 M hydrochloric acid solution so that its concentration becomes 0.5 M?

1. A 50 mL
2. B 100 mL
3. C 120 mL
4. D 290 mL

250 mL of 3 M hydrochloric acid was added to 350 mL of 2 M hydrochloric acid.
What is the concentration of the resulting solution?

1. A 1.45 M
2. B 2.42 M
3. C 2.5 M
4. D 2.9 M

200 mL of distilled water was added to 300 mL of 0.23 M magnesium nitrate solution.
What is the concentration of the nitrate anion in the solution after dilution with water?

1. A 0.138 M
2. B 0.276 M
3. C 0.184 M
4. D 0.46 M

The number of potassium ions in 300 mL of 0.2 M potassium sulphate equals ..........

1. A 7.2 × 10²² ion
2. B 3.6 × 10²² ion
3. C 2.7 × 10²² ion
4. D 6.3 × 10²² ion

What is the percentage of iron in a mole of red iron oxide?
[Fe = 55.86 , O = 16]

1. A 72%
2. B 50%
3. C 42%
4. D 69.9%

Excess hot conc. H₂SO₄ was added to an impure sample of magnetite ore of mass 20 g, and 15 g of the sample was consumed.
What is the percentage of impurities in the sample?

1. A 75%
2. B 25%
3. C 30%
4. D 7.5%

Which substance is completely consumed in the titration process?

1. A The standard solution.
2. B The acid.
3. C The solution of unknown concentration.
4. D The base.

All of the following are oxidation-reduction reactions, except ..........

1. A preparing iron(III) chloride from its elements.
2. B titrating an acidic solution with a standard solution.
3. C thermal decomposition of iron(II) sulphate.
4. D titrating sodium nitrite with acidified KMnO₄.

Which of the following can be used as a 0.1 M standard solution to determine the concentration of chloride ions in an aqueous solution of one of its salts?

1. A HNO₃
2. B Na₂SO₄
3. C NaOH
4. D AgNO₃

What is the standard solution used to determine the concentration of a sodium carbonate solution?

1. A HCl(aq)
2. B KOH(aq)
3. C NaCl(aq)
4. D KHCO₃(aq)

From the following chart:
What term describes the 1 M solutions of NaOH, Na₂SO₄ and NaCl,
and what type of reactions led to the formation of the compounds AgCl, BaSO₄ and Fe(OH)₃?

1. A Standard solutions , oxidation-reduction reactions.
2. B Acidic solutions , neutralization reactions.
3. C Basic solutions , precipitation reactions.
4. D Standard solutions , precipitation reactions.

The following equations represent three chemical reactions:
(1) 2Fe(s) + 3Br₂(l) → 2FeBr₃(s)
(2) AgNO₃(aq) + NaCl(aq) → NaNO₃(aq) + AgCl(s)
(3) Sr(OH)₂(aq) + 2HCl(aq) → SrCl₂(aq) + 2H₂O(l)
Which of the following represents the type of each of reactions (1), (2) and (3)?

1. A (1) : oxidation-reduction , (2) : precipitation , (3) : neutralization.
2. B (1) : oxidation-reduction , (2) : precipitation , (3) : oxidation-reduction.
3. C (1) : precipitation , (2) : neutralization , (3) : neutralization.
4. D (1) : neutralization , (2) : neutralization , (3) : oxidation-reduction.

Which of the following is used to distinguish between pure water and 0.01 M HCl acid?

1. A A piece of copper.
2. B A piece of scandium.
3. C Phenolphthalein indicator.
4. D Bromothymol blue indicator.

Indicator (W) was added to solution (X) and it turned yellow, and indicator (Y) was added to solution (Z) and it also turned yellow.
Which of the following is correct?

1. A Indicator (W): bromothymol blue ; solution (X): CH₃COOH ; indicator (Y): methyl orange ; solution (Z): ammonia solution
2. B Indicator (W): methyl orange ; solution (X): NaOH ; indicator (Y): bromothymol blue ; solution (Z): ammonia solution
3. C Indicator (W): phenolphthalein ; solution (X): NaOH ; indicator (Y): litmus ; solution (Z): H₂CO₃
4. D Indicator (W): litmus ; solution (X): CH₃COOH ; indicator (Y): phenolphthalein ; solution (Z): H₂CO₃

Solution (X) is used to distinguish between Fe²⁺(aq) and Fe³⁺(aq) solutions.
What is the effect of adding drops of the indicators (Y) and (Z) - each separately - to solution (X)?

1. A Effect of adding (Y) to (X): the solution turns yellow ; effect of adding (Z) to (X): the solution turns light green
2. B Effect of adding (Y) to (X): the solution turns blue ; effect of adding (Z) to (X): the solution turns yellow
3. C Effect of adding (Y) to (X): the solution turns pinkish red ; effect of adding (Z) to (X): the solution turns orange
4. D Effect of adding (Y) to (X): the solution turns blue ; effect of adding (Z) to (X): the solution turns light green

Which of the following represents each of the indicators (1) and (2) in the opposite Venn diagram?

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

Phenolphthalein solution is used to distinguish between ..........

1. A HCl(aq) , NaOH(aq)
2. B H₂O(l) , HCl(aq)
3. C the basic reagent of NO₃⁻ , H₂O(l)
4. D the basic reagent of Fe²⁺(aq) and the confirmatory reagent of Fe³⁺(aq).

Potassium hydroxide solution is used to distinguish between each of the following, except ..........

1. A methyl orange and bromothymol blue.
2. B phenolphthalein and litmus.
3. C bromothymol blue and litmus.
4. D phenolphthalein and methyl orange.

Litmus indicator and bromothymol blue indicator cannot be distinguished after adding ..........

1. A the reagent of the Hg⁺ cation
2. B H₂SO₄(aq)
3. C the reagent of the Al³⁺ cation
4. D H₂O(l)

Which of the following gases colours methyl orange and litmus indicators differently when passed through each of them?

1. A NH₃(g)
2. B HCl(g)
3. C CO₂(g)
4. D SO₂(g)

A container holding 10 mL of 1 M hydrochloric acid with drops of methyl orange indicator, to which 5 mL of 1 M sodium hydroxide solution was added.
What change takes place in this mixture?

1. A The colour of methyl orange changes from red to yellow.
2. B The concentration of H⁺ ions increases.
3. C The colour of methyl orange changes from yellow to red.
4. D The colour becomes less intense.

Indicator (X) was added to an aqueous solution containing 0.25 mol of sodium hydroxide and 0.2 mol of hydrochloric acid.
Which indicator (X) was used, and what is its colour in this aqueous solution?

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

Solution (X) is used as a basic reagent for the thiosulphate anion, and solution (Y) is used as a confirmatory reagent for the cations of the third analytical group.
What colour forms when drops of methyl orange indicator are added to each of solutions (X) and (Y)?

1. A (X) : orange , (Y) : red.
2. B (X) : red , (Y) : yellow.
3. C (X) : red , (Y) : orange.
4. D (X) : yellow , (Y) : red.

Three identical samples each contain a mixture of 40 mL of 0.5 M sulphuric acid with 50 mL of 0.4 M sodium hydroxide solution. What is the colour of each of them with the following indicators?

1. A Methyl orange indicator: yellow ; litmus indicator: blue ; bromothymol blue indicator: blue
2. B Methyl orange indicator: orange ; litmus indicator: purple ; bromothymol blue indicator: light green
3. C Methyl orange indicator: red ; litmus indicator: red ; bromothymol blue indicator: blue
4. D Methyl orange indicator: red ; litmus indicator: red ; bromothymol blue indicator: yellow

Bromothymol blue indicator turns green in the mixture made of ..........

1. A 25 mL of 0.1 M Ba(OH)₂ solution + 25 mL of 0.1 M HNO₃ acid
2. B 25 mL of 0.1 M NaOH solution + 25 mL of 0.1 M H₂SO₄ acid
3. C 25 mL of 0.1 M KOH solution + 25 mL of 0.1 M HCl acid
4. D 25 mL of 0.1 M Ca(OH)₂ solution + 25 mL of 0.1 M H₃PO₄ acid

The following statements describe the steps of a titration process (not in order):
(1) : The acid is added dropwise from the burette into the conical flask until the colour of the indicator changes.
(2) : Add a suitable chemical indicator.
(3) : Transfer a known volume of the alkali into a conical flask using the pipette.
(4) : Record the initial burette reading of the acid.
(5) : Record the final burette reading of the acid.
What is the correct order of the steps of the titration process?

1. A (2) → (4) → (1) → (5) → (3)
2. B (3) → (2) → (4) → (1) → (5)
3. C (3) → (4) → (1) → (5) → (2)
4. D (4) → (3) → (1) → (2) → (5)

When 10 mL of 0.5 M sulphuric acid is added to 5 mL of 2 M sodium hydroxide solution during titration, ..........

1. A number of moles of H⁺(aq) = number of moles of OH⁻(aq)
2. B nb < na
3. C number of moles of H₂SO₄ < number of moles of NaOH
4. D (Mb Vb) = (Ma Va)

From the following reaction:
3KOH(aq) + H₃PO₄(aq) → K₃PO₄(aq) + 3H₂O(l)
What volume of 0.2 M potassium hydroxide is needed to titrate 25 mL of 0.1 M phosphoric acid?

1. A 37.5 mL
2. B 25 mL
3. C 12.5 mL
4. D 18.75 mL

30 mL of 0.15 M nitric acid was titrated using 0.1 M sodium bicarbonate solution.
What volume of sodium bicarbonate solution is needed for the titration?

1. A 30 mL
2. B 35 mL
3. C 40 mL
4. D 45 mL

Sodium bisulphate solution reacts with sodium hydroxide solution according to the following equation:
NaHSO₄(aq) + NaOH(aq) → Na₂SO₄(aq) + H₂O(l)
What volume of 0.2 M NaOH solution is needed to react completely with 0.01 mol of sodium bisulphate solution?

1. A 20 mL
2. B 50 mL
3. C 100 mL
4. D 500 mL

23 mL of 1.63 M barium hydroxide solution was titrated with sulphuric acid solution, and the volume of acid consumed at the end point of the reaction was 75 mL. The molarity of the acid equals ..........

1. A 0.5 M
2. B 0.25 M
3. C 0.125 M
4. D 0.05 M

From the opposite reaction:
Na₂CO₃(s) + 2HCl(aq) → 2NaCl(aq) + H₂O(l) + CO₂(g)
On complete titration of 20 mL of 0.5 M sodium carbonate, 50 mL of the standard solution was consumed, whose concentration is ..........

1. A 0.4 M
2. B 0.2 M
3. C 0.02 M
4. D 0.04 M

25 mL of 0.1 M sodium hydroxide is completely neutralized by 20 mL of sulphuric acid.
What is the concentration of the sulphuric acid used?

1. A 0.0313 M
2. B 0.0625 M
3. C 0.125 M
4. D 0.25 M

When 100 mL of 0.1 M HCl acid is mixed with 100 mL of 0.2 M NaOH solution, the result is ..........

1. A a 0.01 M basic solution
2. B a 0.01 M acidic solution
3. C a 0.05 M basic solution
4. D a 0.05 M acidic solution

When 25 mL of sodium hydroxide solution is added to 50 mL of sulphuric acid, all the reactants are consumed.
Which of the following describes the concentration of the sodium hydroxide solution?

1. A Four times the concentration of the sulphuric acid.
2. B Equal to the concentration of the sulphuric acid.
3. C Twice the concentration of the sulphuric acid.
4. D Half the concentration of the sulphuric acid.

22.52 mL of 0.015 M MnO₄⁻ solution was needed to calculate the concentration of Fe²⁺ in 25 mL of a solution of one of its salts, according to the following equation:
MnO₄⁻(aq) + 5Fe²⁺(aq) + 8H⁺(aq) → Mn²⁺(aq) + 5Fe³⁺(aq) + 4H₂O(l)
What is the concentration of the Fe²⁺ solution used?

1. A 0.136 M
2. B 0.068 M
3. C 1.689 × 10⁻³ M
4. D 3.378 × 10⁻⁴ M

From the opposite reaction:
2MnO₄⁻ + 5H₂C₂O₄ + 6H⁺ → 2Mn²⁺ + 10CO₂ + 8H₂O
Titrating 0.134 g of oxalic acid H₂C₂O₄ needed 24.7 mL of permanganate solution, whose concentration is ..........
[H₂C₂O₄ = 90 g/mol]

1. A 5.96 × 10⁻⁴ M
2. B 1.49 × 10⁻³ M
3. C 2.41 × 10⁻² M
4. D 6.03 × 10⁻² M

A mixture of mass 50 g made of the two salts sodium carbonate and sodium chloride needed 1 L of 0.45 M HCl acid to react completely with it, so the concentration of NaCl in the resulting solution is ..........
[NaCl = 58.5 g/mol , Na₂CO₃ = 106 g/mol]

1. A 0.364 M
2. B 0.447 M
3. C 0.6 M
4. D 0.9 M

What volume and concentration of sodium hydroxide solution are needed to completely neutralize 20 mL of 0.5 M sulphuric acid?

1. A Volume: 20 mL ; concentration: 0.5 M
2. B Volume: 40 mL ; concentration: 0.5 M
3. C Volume: 40 mL ; concentration: 0.1 M
4. D Volume: 20 mL ; concentration: 0.1 M

Which of the following represents the volume and concentration of each of the calcium hydroxide solution and the hydrochloric acid needed for neutralization?

1. A Calcium hydroxide: volume x mL , concentration 2y M ; hydrochloric acid: volume 2x mL , concentration y M
2. B Calcium hydroxide: volume 2x mL , concentration y M ; hydrochloric acid: volume x mL , concentration 2y M
3. C Calcium hydroxide: volume x mL , concentration y M ; hydrochloric acid: volume 2x mL , concentration y M
4. D Calcium hydroxide: volume 2x mL , concentration 2y M ; hydrochloric acid: volume x mL , concentration 2y M

What is the number of moles of KOH needed to completely neutralize 20 mL of 1 M H₂SO₄ acid?

1. A 0.01 mol
2. B 0.02 mol
3. C 0.03 mol
4. D 0.04 mol

What volume of 0.1 M HCl acid is needed to react completely with 1 g of pure calcium carbonate?
[CaCO₃ = 100 g/mol]

1. A 100 mL
2. B 150 mL
3. C 200 mL
4. D 250 mL

What is the concentration of hydrochloric acid, 25 mL of which neutralizes 0.84 g of sodium bicarbonate?
[NaHCO₃ = 84 g/mol]

1. A 0.02 M
2. B 0.04 M
3. C 0.2 M
4. D 0.4 M

What volume of 0.2 M sulphuric acid is needed to titrate 500 mL of sodium hydroxide solution, each litre of which contains 1.2 g of the dissolved substance?
[NaOH = 40 g/mol]

1. A 37.5 mL
2. B 50 mL
3. C 75 mL
4. D 100 mL

What mass of Ca(OH)₂ completely neutralizes 100 mL of 0.1 M phosphoric acid?
[Ca = 40 , O = 16 , H = 1]

1. A 0.49 g
2. B 0.74 g
3. C 1.11 g
4. D 2.22 g

15 mL of sodium hydroxide solution is needed to titrate 25 mL of 0.1 M sulphuric acid.
What is the mass of NaOH dissolved in 450 mL of the sodium hydroxide solution used in the titration?
[Na = 23 , O = 16 , H = 1]

1. A 2 g
2. B 4.5 g
3. C 6 g
4. D 6.3 g

0.512 g of a monoprotic acid of molar mass 204.22 g/mol is needed to completely neutralize 36.78 mL of NaOH solution. What is the concentration of the NaOH solution used?

1. A 0.00251 M
2. B 0.0139 M
3. C 0.0682 M
4. D 0.092 M

Titrating 0.307 g of a triprotic acid needed 35.2 mL of 0.106 M NaOH solution.
What is the molar mass of the acid used?

1. A 151.28 g/mol
2. B 165 g/mol
3. C 171 g/mol
4. D 246.84 g/mol

0.45 g of a mineral acid of molar mass 90 g/mol is completely neutralized by 20 mL of 0.5 M KOH solution, so the acid is ..........

1. A monoprotic.
2. B diprotic.
3. C triprotic.
4. D tetraprotic.

0.06 g of a monohydroxy base was dissolved in water to make a solution, and this solution was used up in titrating 15 mL of a 0.1 M monoprotic acid.
What is the molar mass of the base used?

1. A 40 g/mol
2. B 56 g/mol
3. C 60 g/mol
4. D 98 g/mol

When titrating a solution containing 1 g of an impure sample of sodium bicarbonate, 7.15 mL of 0.1 M sulphuric acid was needed to reach the neutralization point.
What is the mass percentage of sodium bicarbonate in the sample?
[NaHCO₃ = 84 g/mol]

1. A 3%
2. B 6%
3. C 12%
4. D 24%

A 0.2 g sample of a mixture containing sodium chloride and sodium hydroxide needed 10 mL of 0.2 M hydrochloric acid to react completely with it.
What is the mass percentage of sodium chloride in the mixture?
[Na = 23 , O = 16 , H = 1]

1. A 80%
2. B 60%
3. C 40%
4. D 20%

10 mL of HCl acid is needed to neutralize 0.3 g of an impure sample of magnesium oxide, and 3 mL of the same acid is needed to neutralize 0.045 g of pure calcium carbonate.
What is the percentage of magnesium oxide in the impure sample?
[MgO = 40 g/mol , CaCO₃ = 100 g/mol]

1. A 20%
2. B 30%
3. C 60%
4. D 80%

Excess dilute hydrochloric acid was added to an impure sample of calcium carbonate of mass 12 g, and 2.64 L of carbon dioxide gas formed (at STP).
What is the degree of purity of the calcium carbonate sample?
[CaCO₃ = 100 g/mol]

1. A 42.75%
2. B 47.88%
3. C 70%
4. D 98.2%

A sample of calcium carbonate of purity 85% and mass 100 g needs, for its titration, 2.5 L of hydrochloric acid of concentration ..........
[CaCO₃ = 100 g/mol]

1. A 0.34 M
2. B 0.4 M
3. C 0.68 M
4. D 0.8 M

An aqueous solution containing 6.5 g of 90% pure NaCl was electrolysed according to the following equation:
2NaCl(aq) + 2H₂O(l) → Cl₂(g) + H₂(g) + 2NaOH(aq)
What volume of 1 M hydrochloric acid is needed to completely neutralize the NaOH produced?
[NaCl = 58.5 g/mol]

1. A 100 mL
2. B 200 mL
3. C 1000 mL
4. D 2000 mL

A sample of magnesium carbonate of mass 1.68 g was divided into two equal parts, and the following was added:
• to the first part, 25 mL of 2 M HCl acid (first case).
• to the second part, 25 mL of 0.25 M H₂SO₄ acid (second case).
What is the volume of the gas produced in each case (at STP)?
[MgCO₃ = 84 g/mol]

1. A In the first case: 140 mL , in the second case: equal to the volume of gas in the first case.
2. B In the first case: 140 mL , in the second case: greater than the volume of gas in the first case.
3. C In the first case: 224 mL , in the second case: less than the volume of gas in the first case.
4. D In the first case: 224 mL , in the second case: equal to the volume of gas in the first case.

A sample of a hydrated salt of mass 4.92 g was heated until its mass became constant at 2.4 g. What is the number of molecules of water of crystallization in the sample?
[H₂O = 18 g/mol]

1. A 8.428 × 10²² Molecule
2. B 4.34 × 10²⁴ Molecule
3. C 14 Molecule
4. D 7 Molecule

When a sample of hydrated calcium chloride was strongly heated, 24.5% of the mass of the sample was lost. What is the molecular formula of the hydrated salt?
[CaCl₂ = 111 g/mol , H₂O = 18 g/mol]

1. A CaCl₂.4H₂O
2. B CaCl₂.3H₂O
3. C CaCl₂.2H₂O
4. D CaCl₂.6H₂O

When 2.68 g of sodium sulphate crystals were strongly heated, 1.26 g of water evaporated. It is concluded from this that the molecular formula of these crystals is ..........
[Na = 23 , S = 32 , O = 16 , H = 1]

1. A Na₂SO₄.H₂O
2. B 2Na₂SO₄.H₂O
3. C Na₂SO₄.7H₂O
4. D Na₂SO₄.8H₂O

What is the number of moles of water of crystallization in one mole of hydrated zinc sulphate crystals whose molar mass is 287.4 g/mol?
[Zn = 65.4 , S = 32 , O = 16 , H = 1]

1. A 5 mol
2. B 6 mol
3. C 7 mol
4. D 8 mol

A sample of hydrated cobalt chloride CoCl₂.6H₂O was strongly heated until its mass became constant at 1.7 g.
What is the number of moles of water vapour driven off from the sample?
[CoCl₂ = 130 g/mol]

1. A 0.156 mol
2. B 0.0156 mol
3. C 0.078 mol
4. D 0.78 mol

If the percentage of water of crystallization in hydrated magnesium sulphate equals 51.22%,
what is the value of (X) in MgSO₄.XH₂O?
[MgSO₄ = 120 g/mol , H₂O = 18 g/mol]

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

A sample of hydrated sodium carbonate Na₂CO₃.XH₂O was completely neutralized by 50 mL of 0.1 M hydrochloric acid. What is the number of moles of water of crystallization in the sample?

1. A 0.025X mol
2. B 0.05X mol
3. C 0.0025X mol
4. D 0.052X mol

A 2 g sample of crystalline sodium carbonate Na₂CO₃.XH₂O needs 0.025 mol of HCl acid for its titration.
What is the value of the number of moles of water of crystallization (X)?
[Na₂CO₃ = 106 g/mol , H₂O = 18 g/mol]

1. A 3 mol
2. B 5 mol
3. C 7 mol
4. D 10 mol

0.2537 g of washing soda crystals (crystalline sodium carbonate) was dissolved in water to make a solution of volume 20 mL. Titrating this volume of the solution needed 10.8 mL of 0.05 M sulphuric acid.
What is the percentage of water of crystallization in these crystals?
[Na₂CO₃ = 106 g/mol]

1. A 22.56%
2. B 34.32%
3. C 46.12%
4. D 77.44%

A sample of CuSO₄.XH₂O of mass 8.84 g was completely dried and its mass became 5.65 g.
What is the number of water molecules in a mole of the hydrated salt?
[CuSO₄ = 159.5 g/mol , H₂O = 18 g/mol]

1. A 1.204 × 10²⁴ Molecule
2. B 1.07 × 10²³ Molecule
3. C 3.01 × 10²⁴ Molecule
4. D 2.14 × 10²³ Molecule

Gravimetric analysis by the precipitation method is carried out by reacting dilute sulphuric acid with ..........

1. A barium chloride solution.
2. B sodium hydroxide solution.
3. C sodium nitrate solution.
4. D copper(II) carbonate salt.

15 mL of 1 M AgNO₃ solution was added to 10 mL of 1 M K₂CrO₄ solution, and a precipitate formed.
Which ions are present in the reaction mixture after the reaction ends?

1. A Ag⁺ , NO₃⁻ , K⁺ , CrO₄²⁻
2. B Ag⁺ , NO₃⁻ , K⁺
3. C K⁺ , CrO₄²⁻
4. D NO₃⁻ , K⁺ , CrO₄²⁻

In a laboratory experiment, 4 mL of 1 M iron(III) chloride solution was mixed with 4 mL of 1 M sodium hydroxide solution.
What can be observed when the reaction ends?

1. A A reddish-brown precipitate forms in a solution of one compound.
2. B A greenish-white precipitate forms in a solution of one compound.
3. C A reddish-brown precipitate forms in a solution of two compounds.
4. D A greenish-white precipitate forms in a solution of two compounds.

When excess silver nitrate solution is added to a water sample containing chloride ions, 1 g of silver chloride precipitates.
What is the mass of the chloride ions in the sample?
Molar mass: AgCl = 143.5 g/mol , Cl⁻ = 35.5 g/mol

1. A 0.25 g
2. B 0.34 g
3. C 0.5 g
4. D 0.75 g

Excess hot conc. H₂SO₄ was added to a pure sample of sodium bromide salt of mass 25.75 g.
What is the mass of the fumes given off that turn a moistened starch paper yellow?
[Na = 23 , Br = 80]

1. A 20 g
2. B 40 g
3. C 80 g
4. D 160 g

All the chloride ions [Cl = 35.5] in a 3.734 g sample of a metal chloride precipitate after 70.9 mL of 0.2 M AgNO₃ solution is added to it. What is the mass percentage of chloride ions in the sample?

1. A 50.52 %
2. B 13.48 %
3. C 1.425 %
4. D 7.391 %

A 3 g sample of an alloy made of Pb and Sn was dissolved in nitric acid, then sulphuric acid was added to it, and 2.37 g of PbSO₄ precipitated, assuming that all the lead was precipitated.
What is the percentage of the element Sn in the sample?
[PbSO₄ = 303 g/mol , Pb = 207 g/mol]

1. A 54%
2. B 1.62%
3. C 1.38%
4. D 46%

To precipitate 80% of the silver ions in 0.5 L of 0.1 M AgNO₃ solution, we use ..........

1. A 1 L of HCl solution (0.05 M).
2. B 0.1 L of CaCl₂ solution (0.2 M).
3. C 0.25 L of NH₄Cl solution (0.15 M).
4. D 0.3 L of MgCl₂ solution (0.2 M).

2 mol of iron(III) hydroxide can be obtained by reacting 1 mol of red iron oxide with hot conc. nitric acid, then reacting the iron salt produced with sodium hydroxide solution.
What mass of iron(III) oxide is needed to precipitate 53.6 g of iron(III) hydroxide?
[Fe₂O₃ = 159.7 g/mol , Fe(OH)₃ = 106.85 g/mol]

1. A 80 g
2. B 71.6 g
3. C 40 g
4. D 35.8 g

A solid mixture of NaCl and Na₂CO₃ of mass 11.15 g was titrated using 200 mL of 0.5 M HCl(aq), then excess lead(II) nitrate solution was added to the solution formed.
What is the mass of the precipitate formed?
[NaCl = 58.5 g/mol , PbCl₂ = 278 g/mol , Na₂CO₃ = 106 g/mol]

1. A 2.78 g
2. B 27.8 g
3. C 13.9 g
4. D 55.6 g

Iron can be extracted from magnetite ore in the same way as iron is extracted from haematite ore in the blast furnace. If 4.959 ton of iron can be produced from 7.87 ton of magnetite ore,
then the percentage purity of the ore equals ..........
[Fe = 55.85 , Fe₃O₄ = 231.55 g/mol]

1. A 31%
2. B 45%
3. C 68%
4. D 87%

One mole of sodium hydroxide solution reacts completely with one mole of acid (X), and 25 mL of acid (X) is needed to react completely with 20 mL of 0.1 M sodium hydroxide solution.
Calculate the concentration of the acid (X) used.

20.2 mL of 0.1 M NaOH solution reacts completely with 20.2 mL of a dibasic acid.
Calculate the concentration of the acid used.

Each litre of a solution contains 12.6 g of the acid H₃XO₃, and 25 mL of this acid reacts with 25 mL of 0.1 M NaOH solution according to the equation:
H₃XO₃ + NaOH → NaH₂XO₃ + H₂O
[H = 1 , O = 16]
Calculate the gram atomic mass of the element (X).

The following chart shows the results of the decomposition of the unstable compound (1):
Write the balanced symbolic equation for the reaction of each of:
(1) gas (2) with oxygen.
(2) the hot concentrated liquid (3) with copper.

Calculate the mass of the solid remaining after strongly heating a 5 g sample of the compound Na₂B₄O₇.10H₂O, after all the water of hydration has evaporated.
[Na₂B₄O₇ = 201.2 g/mol , H₂O = 18 g/mol]

An impure sample of hydrogen peroxide of mass 5 g decomposes in the presence of MnO₂, forming 1.12 L of oxygen gas (at STP), according to the equation:
2H₂O₂(aq) → 2H₂O(l) + O₂(g)
[H = 1 , O = 16]
Calculate the percentage purity of the hydrogen peroxide in the sample.

Calculate the mass of the precipitate formed by adding 10 mL of 0.25 mol/L sodium hydroxide solution to excess aluminium nitrate solution.
[Al = 27 , O = 16 , H = 1]

When 200 mL of 0.2 M sulphuric acid is added to 300 mL of 0.2 M calcium hydroxide according to the following equation:
H₂SO₄ + Ca(OH)₂ → CaSO₄ + 2H₂O
Which of the following represents the concentration of the substance left unreacted?
(Sample exam 2026)

1. A 0.080 M
2. B 0.040 M
3. C 0.066 M
4. D 0.0100 M

44.8 g of potassium hydroxide was dissolved in water to make 500 mL of solution, and 10 mL of this solution was titrated using 0.2 M sulphuric acid.
Which of the following represents the volume of acid consumed?
[K = 39 , H = 1 , O = 16]
(Sample exam 2026)

1. A 8 mL
2. B 40 mL
3. C 180 mL
4. D 160 mL

14.3 g of hydrated sodium carbonate Na₂CO₃.10H₂O was dissolved in water to form a solution of volume 500 mL, and 25 mL of this solution was titrated with 25 mL of hydrochloric acid.
Which of the following represents the concentration of the hydrochloric acid?
[Na = 23 , C = 12 , O = 16 , H = 1]
(Sample exam 2026)

1. A 0.1 M
2. B 0.2 M
3. C 0.3 M
4. D 0.4 M

A 200 mL solution of 0.01 M sodium hydroxide: which of the following represents the mass of sodium hydroxide that must be added so that the concentration of the solution becomes 0.7 M?
[NaOH = 40 g/mol]
(Sample exam 2026)

1. A 0.138 g
2. B 0.381 g
3. C 5.52 g
4. D 52.5 g

0.5 g of a metal chloride salt (MCl) was dissolved in water, and excess silver nitrate was added to the solution, so 0.963 g of silver chloride precipitated. The gram atomic mass of the metal M equals ..........
[Ag = 108 g/mol , Cl = 35.5 g/mol]
(Sample exam 2026)

1. A 39
2. B 23
3. C 40
4. D 24

A 0.2 M potassium hydroxide solution of volume (X) had 20 mL of distilled water added to it, and 20 mL of the resulting solution was titrated with a sulphuric acid solution containing 0.1176 g of the acid.
Which of the following represents the volume of potassium hydroxide (X)?
[H = 1 , S = 32 , O = 16]
(Sample exam 2026)

1. A 30 mL
2. B 20 mL
3. C 50 mL
4. D 40 mL

100 mL of 0.5 M calcium hydroxide was added to 200 mL of 0.6 M hydrochloric acid according to the following equation:
2HCl + Ca(OH)₂ → CaCl₂ + 2H₂O
Which of the following represents the concentration of the reactant left over?
(Sample exam 2026)

1. A 0.2 M
2. B 0.0667 M
3. C 0.633 M
4. D 0.316 M

A sample of hydrated crystals of acid (A) (A.XH₂O) of mass 2.52 g was dissolved in distilled water to make a solution of volume 250 mL. 25 mL of this solution was titrated with 0.08 M sodium hydroxide solution containing 0.16 g of the solute.
Which of the following represents the number of molecules of water of crystallization (X) and the type of the acid?
[NaOH = 40 g/mol , molar mass of the acid = 90 g/mol]
(Sample exam 2026)

1. A X = 2 and the acid is diprotic.
2. B X = 1 and the acid is monoprotic.
3. C X = 2 and the acid is triprotic.
4. D X = 3 and the acid is triprotic.

An impure sample of aluminium sulphate Al₂(SO₄)₃ of mass 5 g was dissolved in water, then excess ammonia solution was added until aluminium hydroxide was completely precipitated. The precipitate was separated and dried, and its mass was 2.03 g.
Which of the following represents the percentage of aluminium in the sample?
[Al = 27 , S = 32 , N = 14 , O = 16 , H = 1]
(Sample exam 2026)

1. A 85.95%
2. B 14.05%
3. C 52.5%
4. D 8.75%

A mixture of sodium phosphate and potassium iodide of mass 12 g was dissolved in water, and excess silver nitrate solution was added to it, forming a yellow precipitate of mass X g. Then excess ammonium hydroxide solution was added, and a precipitate of mass 8.5 g remained.
Which of the following represents the mass of the precipitate (X)?
[Ag = 108 , K = 39 , Na = 23 , I = 127 , P = 31 , O = 16 , N = 14]
(Sample exam 2026)

1. A 6 g
2. B 8.5 g
3. C 15.252 g
4. D 23.82 g

Given that 16 mL of potassium hydroxide solution is needed to titrate 32 mL of sulphuric acid,
which of the following represents the concentration of the sulphuric acid?
(Sample exam 2026)

1. A Equal to the concentration of the potassium hydroxide.
2. B Half the concentration of the potassium hydroxide.
3. C A quarter of the concentration of the potassium hydroxide.
4. D Four times the concentration of the potassium hydroxide.

Four solutions are produced by dissolving equal masses of four different substances in distilled water, and all of them have the same volume.
Which of these solutions has the lowest concentration?
[Ca = 40 , K = 39 , O = 16 , H = 1 , Li = 7 , Na = 23 , Cl = 35.5]
(Sample exam 2026)

1. A LiCl
2. B KOH
3. C NaCl
4. D Ca(OH)₂

When 45 g of a pure sample of hydrated barium chloride BaCl₂.2H₂O is dissolved in 500 mL of distilled water, 84.2 mL of the resulting solution is needed to precipitate all the sulphate anions produced by dissolving 10 g of hydrated sodium sulphate Na₂SO₄.XH₂O in water.
Which of the following represents the chemical formula of the hydrated sodium sulphate?
[BaCl₂.2H₂O = 244 g/mol , BaCl₂ = 208 g/mol , Na₂SO₄ = 142 g/mol]
(Sample exam 2026)

1. A Na₂SO₄.5H₂O
2. B Na₂SO₄.7H₂O
3. C Na₂SO₄.10H₂O
4. D Na₂SO₄.8H₂O

The opposite figure shows the titration of a sodium hydroxide solution using hydrochloric acid.
When the neutralization point is reached, the burette reading becomes ..........
(Sample exam 2026)

1. A 5 mL
2. B 6.5 mL
3. C 1.5 mL
4. D 11.5 mL

An impure sample of solid magnesium chloride of mass 10 g reacted completely with conc. sulphuric acid, then excess sodium carbonate solution was added to the solution of the salt produced, and a precipitate of mass 7 g formed.
Which of the following represents the percentage of magnesium chloride in the sample?
[Mg = 24 , Na = 23 , C = 12 , Cl = 35.5 , O = 16 , S = 32]
(Sample exam 2026)

1. A 16.79%
2. B 20.84%
3. C 79.16%
4. D 83.84%

When a sample of hydrated iron chloride FeClx.6H₂O of mass 5.34 g is strongly heated, 60.08% of the mass of the sample remains when the mass becomes constant. The oxidation number of iron (x) in this compound equals ..........
[Fe = 56 , Cl = 35.5 , H = 1 , O = 16]
(Sample exam 2026)

1. A +1
2. B +2
3. C +3
4. D +6

When an alkaline solution of concentration (M) is titrated with a 0.5 M acid, at the neutralization point the volume of acid consumed was found to equal the volume of the alkali.
Which of the following choices represents the acid and the alkali?
(Sample exam 2026)

1. A Hydrochloric acid and calcium hydroxide.
2. B Sulphuric acid and potassium hydroxide.
3. C Hydrochloric acid and potassium hydroxide.
4. D Sulphuric acid and calcium hydroxide.

12 g of a mixture of the salts potassium chloride and potassium carbonate was dissolved in water, then excess magnesium sulphate solution was added to the solution, and a precipitate of mass 5 g formed.
Which of the following represents the percentage of potassium chloride in the mixture?
[K = 39 , C = 12 , O = 16 , Mg = 24]
(Sample exam 2026)

1. A 35.44%
2. B 68.45%
3. C 31.55%
4. D 40.91%

When 0.2 mol of the anhydrous salt XCl₂ combines with 7.2 g of water, a hydrated salt with the chemical formula XCl₂.nH₂O forms.
Which of the following represents the value of (n)?
[H = 1 , O = 16]
(Sample exam 2026)

1. A 2
2. B 4
3. C 6
4. D 8

9.636 g of CuSO₄.XH₂O was dissolved in water, then excess BaCl₂ solution was added to it, and a precipitate of mass 9 g formed.
Which of the following represents the value of (X)?
[Ba = 137 , S = 32 , O = 16 , Cu = 63.5 , Cl = 35.5 , H = 1]
(1st session 2025)

1. A 7
2. B 6
3. C 5
4. D 4

A pure sample of sodium carbonate of mass 5.3 g was dissolved in water, then 100 mL of HCl (0.5 M) was added to it, then excess magnesium chloride solution.
Which of the following represents the mass of the precipitate formed?
[Mg = 24 , C = 12 , O = 16 , H = 1 , Cl = 35.5 , Na = 23]
(1st session 2025)

1. A 4.20 g
2. B 2.10 g
3. C 1.05 g
4. D 8.40 g

20 mL of 0.1 M clear limewater was added to 12 mL of 0.5 M hydrochloric acid, and after a sufficient period of time, 10 mL of sodium hydroxide solution was added to complete the titration.
Which of the following represents the concentration of the sodium hydroxide solution?
(Sample exam 2025)

1. A 0.05 M
2. B 0.1 M
3. C 0.2 M
4. D 0.45 M

In the hydrated salt MCl₂.XH₂O, 0.4 mol of the anhydrous salt is bound to 14.4 g of water. Given that the molar mass of the hydrated salt is 244 g/mol, the atomic mass of the metal M equals ..........
[Cl = 35.5 , O = 16 , H = 1]
(Sample exam 2025)

1. A 24 g/mol
2. B 137 g/mol
3. C 40 g/mol
4. D 172 g/mol

A 10 mL solution of 0.5 M hydrochloric acid reacted completely with 20 mL of a solution containing 0.5 g of a mixture of sodium carbonate and sodium chloride.
The mass of the chloride ion in the mixture is ..........
[Na = 23 , Na₂CO₃ = 106 , NaCl = 58.5 , Cl = 35.5]
(2nd session 2024)

1. A 0.143 g
2. B 0.265 g
3. C 0.235 g
4. D 0.207 g

Excess AgNO₃ was added to a solution containing an equal number of moles of sodium chloride and magnesium chloride, and 12 g of a white precipitate formed. The masses of sodium chloride and magnesium chloride in grams are ..........
[NaCl = 58.5 g/mol , MgCl₂ = 95 g/mol , AgCl = 143.5 g/mol]
(2nd session 2024)

1. A NaCl = 2.65 g , MgCl₂ = 1.63 g
2. B NaCl = 1.63 g , MgCl₂ = 2.65 g
3. C NaCl = 4.305 g , MgCl₂ = 3.65 g
4. D NaCl = 3.65 g , MgCl₂ = 4.305 g

An amount of water was added to 100 mL of 0.4 M sulphuric acid to dilute it. 8 mL of the diluted acid was neutralized by 20 mL of 0.2 M potassium hydroxide.
The volume of water that must be added to dilute the acid is ..........
(1st session 2024)

1. A 40 mL
2. B 60 mL
3. C 100 mL
4. D 160 mL

When 200 mL of distilled water is added to 0.5 L of 0.1 M NaOH solution,
the concentration of the solution becomes ..........
(2nd session 2021)

1. A 0.714 M
2. B 0.0714 M
3. C 7.14 M
4. D 4.17 M

To determine the concentration of a silver nitrate solution, a standard solution of .......... is used.
(Trial exam / March 2023)

1. A Na₃PO₄
2. B NaHCO₃
3. C HNO₃
4. D CH₃COOK

Excess hot conc. sulphuric acid was added to 0.1 mol of magnetic iron oxide, then excess sodium hydroxide was added to the products. The total mass of the precipitates formed is ..........
[Given the molecular masses: Fe(OH)₃ = 107 , Fe(OH)₂ = 90]
(2nd session 2023)

1. A 30.4 g
2. B 19.7 g
3. C 152 g
4. D 60.8 g

When sodium hydroxide solution is added to 10 mL of 0.1 M aluminium sulphate solution to obtain a clear solution, the mass of sodium hydroxide needed for the reaction equals ..........
[Given that the molar mass of NaOH = 40 g/mol]
(Trial exam / March 2023)

1. A 2.40 g
2. B 320 g
3. C 0.320 g
4. D 0.24 g

20 mL of 0.1 M NaOH solution was titrated with 0.1 M HCl acid solution. If the hydrochloric acid is replaced by 0.1 M sulphuric acid, the volume of sulphuric acid used is ..........
(Trial exam / June 2021)

1. A half the volume of HCl acid
2. B twice the volume of HCl acid
3. C equal to the volume of HCl acid
4. D twice the volume of the alkali NaOH

When NaOH solution is titrated with dilute sulphuric acid solution, if the two solutions have the same concentration, then at neutralization the volume of acid used is ..........
(1st session 2021)

1. A equal to the volume of the alkali.
2. B half the volume of the alkali.
3. C twice the volume of the alkali.
4. D four times the volume of the alkali.

0.125 mol of hot conc. sulphuric acid reacted with excess sodium nitrate, and when the nitric acid produced was titrated, it was neutralized by 200 mL of sodium hydroxide solution. The concentration of the sodium hydroxide is ..........
[Given the molar masses: H₂SO₄ = 98 g/mol , HNO₃ = 63 g/mol]
(Trial exam / March 2023)

1. A 6.25 M
2. B 0.12 M
3. C 0.625 M
4. D 1.25 M

14.3 g of hydrated sodium carbonate Na₂CO₃.XH₂O was dissolved in water and the volume was made up to one litre, and 25 mL of this solution was neutralized with 25 mL of 0.1 mol/L hydrochloric acid.
The percentage of water of crystallization equals ..........
[O = 16 , C = 12 , Na = 23]
(Trial exam / May 2021)

1. A 31.65%
2. B 15.73%
3. C 25.87%
4. D 62.94%

A sample containing a mixture of the two salts sodium chloride and sodium phosphate of mass 10 g was dissolved in water, and excess aqueous barium chloride solution was added to it. The mass of the precipitate formed was 6 g, so the percentage of sodium phosphate in the sample is ..........
[Ba = 137 , Na = 23 , P = 31 , O = 16]
(Trial exam / May 2021)

1. A 65.5%
2. B 49.05%
3. C 32.7%
4. D 16.35%

To distinguish between two solutions that are both blue, one containing litmus indicator and the other containing bromothymol blue indicator, a solution of .......... can be used.
(2nd session 2023)

1. A H₂SO₄
2. B NH₄OH
3. C Na₂CO₃
4. D NaCl

1 L of 0.3 M calcium chloride solution was added to 1 L of 0.4 M sulphuric acid, then barium hydroxide solution was added to neutralize the excess acid, and a precipitate formed. The number of moles of excess acid and the mass of the precipitate formed are ..........
[Given the molar masses: Ba(OH)₂ = 171 g/mol , BaSO₄ = 233 g/mol , H₂SO₄ = 98 g/mol]
(1st session 2023)

1. A 46.6 g / 0.2 mol
2. B 93.2 g / 0.1 mol
3. C 23.3 g / 0.1 mol
4. D 69.9 g / 0.3 mol

4 g of impure sodium chloride was dissolved in water, and excess silver nitrate solution was added to it, so 3.52 g of silver chloride precipitated. The mass percentage of the chloride ion in the sample equals ..........
[Ag = 108 , Cl = 35.5]
(Trial exam / June 2021)

1. A 21.77%
2. B 20.8%
3. C 22.8%
4. D 19.77%

2 g of (impure) barium chloride was dissolved in water, and excess lead(II) nitrate solution was added to it. The mass of the precipitate was 1 g, so the percentage of the chloride anion in the sample equals ..........
[Cl = 35.5 , Ba = 137 , Pb = 207]
(2nd session 2021)

1. A 19.31%
2. B 46.3%
3. C 28.3%
4. D 12.77%

3.4 g of (impure) potassium chloride was dissolved in water, and excess silver nitrate solution was added to it, so 6.7 g of silver chloride precipitated. The mass percentage of the chloride ion in the sample equals ..........
[K = 39 , Cl = 35.5 , Ag = 108]
(1st session 2021)

1. A 24.5%
2. B 46.7%
3. C 48.7%
4. D 94.1%

A mixture of calcium hydroxide and calcium chloride of mass 4 g needed 100 mL of 0.5 M HCl acid for its titration.
The percentage of calcium hydroxide in the mixture is ..........
[Ca = 40 , O = 16 , H = 1 , Cl = 35.5]
(1st session 2022)

1. A 7.5%
2. B 46.25%
3. C 53.57%
4. D 92.50%

Excess barium chloride solution was added to the solution of an impure sample of potassium sulphate of mass 4 g, and a precipitate of mass 4.66 g formed. The percentage of impurities in the sample equals ..........
[Ba = 137 , S = 32 , O = 16 , K = 39 , H = 1]
(1st session 2022)

1. A 87%
2. B 13%
3. C 67.5%
4. D 32.5%

A hydrated salt in which the percentage of water is 36.072%, and each mole of it is bound to five moles of water of crystallization. The molecular weight of the anhydrous salt equals ..........
[H₂O = 18]
(1st session 2024)

1. A 90 g
2. B 159.5 g
3. C 249.5 g
4. D 250 g

An impure sample of iron(III) chloride of mass 3 g was dissolved in water, then the reagent of the third analytical group was added to it, producing 1.6 g of precipitate. The percentage of iron in the sample equals ..........
[H = 1 , Fe = 56 , Cl = 35.5 , O = 16]
(2nd session 2022)

1. A 80.7%
2. B 62.76%
3. C 27.9%
4. D 33.1%

A mixture of sodium carbonate and sodium chloride of mass 0.4 g was titrated with 20 mL of 0.05 M hydrochloric acid, so the percentage of sodium chloride in the sample equals ..........
[Na = 23 , O = 16 , H = 1 , C = 12 , Cl = 35.5]
(2nd session 2022)

1. A 86.75%
2. B 73.5%
3. C 26.5%
4. D 13.25%

20 mL of 0.1 mol/L sodium hydroxide solution was added to a sulphuric acid solution of volume 10 mL and concentration 0.2 mol/L.
Which of the following represents the type of the resulting solution and its effect on the colour of the indicator?
(Trial exam / May 2021)

1. A Neutral , turns bromothymol blue green
2. B Acidic , turns phenolphthalein red
3. C Acidic , turns methyl orange red
4. D Basic , turns litmus solution blue