I85PREP
⌘ K
Slovakia Maturita Chemistry study materials
Slovakia Maturita Chemistry study resources

Slovakia Maturita Chemistry practice questions

One question at a time. Build your Slovakia Maturita Chemistry understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1General chemistry: structure of matter, atomic structure, periodic table, bonding

Which subatomic particle determines the identity of a chemical element?

  1. The electron
  2. The photon
  3. The neutron
  4. The proton Correct answer.

Explanation

The number of protons in the nucleus (atomic number Z) uniquely defines the element. Changing the proton count changes the element itself, while changing neutrons or electrons gives isotopes or ions of the same element.

Question 2General chemistry: structure of matter, atomic structure, periodic table, bonding

An atom of an element has the electron configuration 1s² 2s² 2p⁶ 3s¹. To which group of the periodic table does it belong?

  1. Group 18
  2. Group 2
  3. Group 17
  4. Group 1 Correct answer.

Explanation

The single electron in the 3s orbital is the outermost (valence) electron. Elements with one valence s electron are placed in Group 1 (the alkali metals).

Question 3General chemistry: structure of matter, atomic structure, periodic table, bonding

Which type of bond is formed when electrons are transferred from a metal atom to a non-metal atom?

  1. Hydrogen bond
  2. Metallic bond
  3. Covalent bond
  4. Ionic bond Correct answer.

Explanation

Ionic bonding involves complete transfer of valence electrons, creating oppositely charged ions held together by electrostatic attraction. This typically occurs between a metal with low ionisation energy and a non-metal with high electron affinity.

Question 4General chemistry: structure of matter, atomic structure, periodic table, bonding

How many electrons can the third shell (n = 3) hold at maximum?

  1. 2
  2. 32
  3. 8
  4. 18 Correct answer.

Explanation

The maximum number of electrons in a shell is given by 2n². For n = 3 this gives 2 × 9 = 18 electrons, distributed among the 3s, 3p and 3d subshells.

Question 5General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following statements about isotopes of the same element is correct?

  1. They have the same mass number but different atomic numbers
  2. They have different numbers of protons and different numbers of electrons
  3. They have the same number of neutrons but different numbers of protons
  4. They have the same number of protons but different numbers of neutrons Correct answer.

Explanation

Isotopes are atoms of the same element, so they share the same atomic number (proton count). They differ only in the number of neutrons, which changes the mass number.

Question 6General chemistry: structure of matter, atomic structure, periodic table, bonding

Which group of the periodic table contains the noble gases?

  1. Group 2
  2. Group 18 Correct answer.
  3. Group 1
  4. Group 17

Explanation

The noble gases occupy Group 18 (the far-right column). Their atoms have full outer electron shells, which makes them very unreactive.

Question 7General chemistry: structure of matter, atomic structure, periodic table, bonding

What is the shape of a methane (CH₄) molecule according to VSEPR theory?

  1. Linear
  2. Trigonal planar
  3. Tetrahedral Correct answer.
  4. Bent

Explanation

Carbon in methane has four bonding pairs and no lone pairs, giving a steric number of four. VSEPR theory places these four electron pairs as far apart as possible, producing a tetrahedral geometry with bond angles of about 109.5°.

Question 8General chemistry: structure of matter, atomic structure, periodic table, bonding

Which type of bonding holds the atoms together within a crystal of sodium chloride?

  1. Ionic bonding Correct answer.
  2. Covalent bonding
  3. Metallic bonding
  4. Van der Waals forces

Explanation

Sodium chloride is built from Na⁺ and Cl⁻ ions arranged in a lattice, held together by strong electrostatic attraction between oppositely charged ions. This is the defining feature of ionic bonding.

Question 9General chemistry: structure of matter, atomic structure, periodic table, bonding

Which element has the electron configuration 1s² 2s² 2p⁶ 3s² 3p⁵?

  1. Fluorine
  2. Chlorine Correct answer.
  3. Sulfur
  4. Argon

Explanation

The configuration totals 17 electrons, matching the atomic number of chlorine. The seven valence electrons (3s² 3p⁵) place chlorine in Group 17.

Question 10General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following correctly lists the elements in order of increasing first ionisation energy?

  1. Na < Mg < Al < Si Correct answer.
  2. Mg < Na < Si < Al
  3. Na < Al < Mg < Si
  4. Si < Al < Mg < Na

Explanation

Across a period, increasing nuclear charge and decreasing atomic radius generally raise first ionisation energy. The order Na < Mg < Al < Si follows this trend, giving silicon the highest value of the four.

Question 11General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following molecules is polar overall?

  1. BF₃
  2. HCl Correct answer.
  3. CH₄
  4. CO₂

Explanation

HCl has a polar bond and a linear geometry with only two atoms, so the bond dipole is not cancelled and the molecule is polar. In the other molecules, symmetric geometry causes the individual bond dipoles to cancel.

Question 12General chemistry: structure of matter, atomic structure, periodic table, bonding

Which type of orbital is described by the quantum numbers n = 3 and l = 2?

  1. 3f
  2. 3p
  3. 3s
  4. 3d Correct answer.

Explanation

The principal quantum number n = 3 gives the shell, and the azimuthal quantum number l = 2 corresponds to a d subshell. Together these define the 3d orbital.

Question 13General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following properties increases across a period from left to right?

  1. Electronegativity Correct answer.
  2. Number of electron shells
  3. Metallic character
  4. Atomic radius

Explanation

Electronegativity rises across a period because the effective nuclear charge increases while atomic radius decreases, allowing the nucleus to attract bonding electrons more strongly.

Question 14General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following substances has a giant covalent (network) structure?

  1. Copper
  2. Diamond Correct answer.
  3. Iodine
  4. Sodium chloride

Explanation

Diamond consists of carbon atoms each covalently bonded to four others in an extended three-dimensional network. This giant covalent structure explains its extreme hardness and very high melting point.

Question 15General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following molecules contains only a single covalent bond and a lone pair on the central atom?

  1. O₂
  2. H₂O Correct answer.
  3. N₂
  4. CO₂

Explanation

In water, oxygen forms two single O–H bonds and retains two lone pairs. This combination of two bonding pairs and two lone pairs produces its bent geometry.

Question 16General chemistry: structure of matter, atomic structure, periodic table, bonding

What is the oxidation state of sulfur in the sulfate ion, SO₄²⁻?

  1. −2
  2. +6 Correct answer.
  3. +2
  4. +4

Explanation

Oxygen is assigned −2, giving a total of −8 for four oxygen atoms. The ion carries a −2 charge, so the sulfur must be +6 to make the sum equal −2.

Question 17General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following pairs of atoms would form the most polar covalent bond?

  1. H and Cl
  2. C and C
  3. C and H
  4. H and F Correct answer.

Explanation

Bond polarity depends on the electronegativity difference between the two atoms. Fluorine is the most electronegative element, so the H–F bond has the largest electronegativity difference among these pairs.

Question 18General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following statements about the modern periodic table is correct?

  1. Elements are arranged in order of increasing atomic number Correct answer.
  2. Elements are arranged in order of increasing atomic mass
  3. Elements in a group have the same number of electron shells
  4. Elements in a period share the same number of valence electrons

Explanation

The modern periodic table orders elements by increasing atomic number (proton count), which corrects anomalies of earlier mass-based arrangements. Elements in the same group share valence electron patterns, while elements in the same period share the same number of shells.

Question 19General chemistry: structure of matter, atomic structure, periodic table, bonding

An atom of phosphorus-31 (Z = 15) contains how many neutrons?

  1. 46
  2. 16 Correct answer.
  3. 31
  4. 15

Explanation

The mass number is the sum of protons and neutrons. For phosphorus-31, subtracting the proton number 15 from 31 gives 16 neutrons.

Question 20General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following best explains why magnesium has a higher first ionisation energy than sodium?

  1. Magnesium has more electron shells than sodium
  2. Magnesium has a greater effective nuclear charge acting on the same shell Correct answer.
  3. Magnesium has more neutrons in its nucleus
  4. Magnesium has a larger atomic radius than sodium

Explanation

Both elements lose an electron from the third shell, but magnesium has one more proton, giving a greater effective nuclear charge. This holds the outer electrons more tightly, raising the ionisation energy.

Question 21General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following species has the same electron configuration as the neon atom?

  1. S²⁻
  2. Na⁺
  3. Mg²⁺ Correct answer.
  4. Cl⁻

Explanation

A magnesium atom (Z = 12) losing two electrons leaves 10 electrons, matching the neon configuration 1s² 2s² 2p⁶.

Question 22General chemistry: structure of matter, atomic structure, periodic table, bonding

Why does the boiling point of water greatly exceed that of hydrogen sulfide, H₂S?

  1. Water is a non-polar molecule while H₂S is polar
  2. Water molecules form hydrogen bonds, whereas H₂S molecules do not Correct answer.
  3. H₂S has a giant covalent structure
  4. H₂S has a higher molar mass than water

Explanation

Oxygen is highly electronegative and small, so O–H bonds allow water molecules to form strong intermolecular hydrogen bonds. Sulfur is larger and less electronegative, so H₂S relies only on weaker dipole–dipole and dispersion forces, giving a much lower boiling point.

Question 23General chemistry: structure of matter, atomic structure, periodic table, bonding

An element has a first ionisation energy much lower than its second, and its second much lower than its third. Which group is it most likely to occupy?

  1. Group 13
  2. Group 17
  3. Group 1
  4. Group 2 Correct answer.

Explanation

A large jump between the second and third ionisation energies indicates that the third electron is removed from a full inner shell after two valence electrons are lost. Two valence electrons are characteristic of Group 2 elements.

Question 24General chemistry: structure of matter, atomic structure, periodic table, bonding

Which statement correctly describes the bonding in a molecule of carbon dioxide?

  1. Two double bonds with a linear arrangement of atoms Correct answer.
  2. One triple bond and one single bond with a linear arrangement
  3. Two single bonds with a bent arrangement of atoms
  4. Two double bonds with a bent arrangement of atoms

Explanation

Each oxygen forms a double bond with carbon, giving two electron domains around the central carbon. Two domains produce a linear geometry with a bond angle of 180°.

Question 25General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following correctly explains why the atomic radius decreases from lithium to fluorine across period 2?

  1. Nuclear charge increases while electrons are added to the same shell Correct answer.
  2. Shielding by inner electrons increases faster than nuclear charge
  3. The number of neutrons decreases steadily
  4. Electrons are added to new shells, pulling the atom inward

Explanation

Across a period, protons are added to the nucleus and electrons to the same outer shell. Because inner-shell shielding stays roughly constant while nuclear charge grows, the outer electrons are pulled closer, shrinking the radius.

Question 26General chemistry: structure of matter, atomic structure, periodic table, bonding

Which statement correctly describes the number of protons and neutrons in an atom of chlorine-37 (Z = 17)?

  1. 17 protons and 20 neutrons Correct answer.
  2. 37 protons and 17 neutrons
  3. 17 protons and 37 neutrons
  4. 20 protons and 17 neutrons

Explanation

The atomic number Z gives the number of protons, which is 17 for chlorine. The mass number (37) is the sum of protons and neutrons, so the number of neutrons is 37 − 17 = 20.

Question 27General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following elements is a transition metal?

  1. Iron Correct answer.
  2. Sulfur
  3. Calcium
  4. Argon

Explanation

Transition metals occupy the d-block of the periodic table (groups 3–12). Iron (Fe) is in group 8, so it is a transition metal.

Question 28General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following bonds is formed by the electrostatic attraction between oppositely charged ions?

  1. An ionic bond in MgO Correct answer.
  2. A covalent bond in H₂
  3. A metallic bond in copper
  4. A hydrogen bond in water

Explanation

An ionic bond results from the electrostatic attraction between cations and anions. In magnesium oxide, Mg²⁺ and O²⁻ ions are held together by this attraction.

Question 29General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following molecules has a trigonal pyramidal shape?

  1. BF₃
  2. NH₃ Correct answer.
  3. CO₂
  4. H₂O

Explanation

According to VSEPR theory, ammonia (NH₃) has three bonding pairs and one lone pair on nitrogen. The four electron pairs adopt a tetrahedral arrangement, but the molecular shape is trigonal pyramidal.

Question 30General chemistry: structure of matter, atomic structure, periodic table, bonding

Which of the following correctly explains why the first ionisation energy generally increases across a period from left to right?

  1. The number of neutrons in the nucleus increases, attracting electrons more strongly.
  2. The number of electron shells increases, so outer electrons are farther from the nucleus.
  3. The atomic radius increases, making it easier to remove an electron.
  4. The nuclear charge increases while electrons are added to the same shell, so the effective nuclear charge rises. Correct answer.

Explanation

Across a period, protons are added to the nucleus and electrons enter the same outer shell. The increased nuclear charge is only partly shielded, so the effective nuclear charge increases and holds the outer electrons more tightly.

Question 31Chemical calculations, stoichiometry and quantitative relationships

How many moles of particles are contained in 1.204 × 10²⁴ molecules of water? (Avogadro constant N_A = 6.02 × 10²³ mol⁻¹)

  1. 4.0 mol
  2. 2.0 mol Correct answer.
  3. 0.5 mol
  4. 1.0 mol

Explanation

The amount of substance is the number of particles divided by the Avogadro constant: n = N / N_A = 1.204 × 10²⁴ / 6.02 × 10²³ = 2.0 mol.

Question 32Chemical calculations, stoichiometry and quantitative relationships

What is the molar mass of calcium carbonate, CaCO₃? (A_r: Ca = 40, C = 12, O = 16)

  1. 100 g/mol Correct answer.
  2. 116 g/mol
  3. 68 g/mol
  4. 56 g/mol

Explanation

The molar mass in g/mol equals the sum of the relative atomic masses: 40 + 12 + (3 × 16) = 100 g/mol.

Question 33Chemical calculations, stoichiometry and quantitative relationships

What is the mass of 0.25 mol of sodium hydroxide, NaOH? (M = 40 g/mol)

  1. 10 g Correct answer.
  2. 0.25 g
  3. 160 g
  4. 40 g

Explanation

Mass equals amount of substance multiplied by molar mass: m = n × M = 0.25 mol × 40 g/mol = 10 g.

Question 34Chemical calculations, stoichiometry and quantitative relationships

Which statement correctly describes the molar volume of an ideal gas at standard temperature and pressure (0 °C, 101.325 kPa)?

  1. It is 22.4 dm³ for one gram of gas.
  2. It depends on the identity of the gas.
  3. It is 22.4 dm³ for one mole of gas. Correct answer.
  4. It is 24.0 dm³ for one mole of gas.

Explanation

At STP (0 °C, 101.325 kPa) one mole of any ideal gas occupies 22.4 dm³, independent of the gas identity. The value 24.0 dm³/mol applies at room conditions (25 °C).

Question 35Chemical calculations, stoichiometry and quantitative relationships

How many atoms are present in 2 moles of oxygen gas, O₂? (N_A = 6.02 × 10²³ mol⁻¹)

  1. 2.408 × 10²⁴ atoms Correct answer.
  2. 1.204 × 10²⁴ atoms
  3. 4.816 × 10²⁴ atoms
  4. 6.02 × 10²³ atoms

Explanation

Each O₂ molecule contains two oxygen atoms, so 2 mol of O₂ contains 4 mol of atoms. Multiplying by N_A gives 4 × 6.02 × 10²³ = 2.408 × 10²⁴ atoms.

Question 36Chemical calculations, stoichiometry and quantitative relationships

What is the mass percentage of oxygen in sulfuric acid, H₂SO₄? (M = 98 g/mol, A_r: O = 16)

  1. 16.3 %
  2. 49.0 %
  3. 32.7 %
  4. 65.3 % Correct answer.

Explanation

Four oxygen atoms contribute 4 × 16 = 64 g/mol. The mass fraction is 64 / 98 = 0.653, i.e. 65.3 %.

Question 37Chemical calculations, stoichiometry and quantitative relationships

How many grams of NaCl are needed to prepare 250 cm³ of a 0.200 mol/dm³ solution? (M = 58.5 g/mol)

  1. 11.7 g
  2. 2.93 g Correct answer.
  3. 0.050 g
  4. 5.85 g

Explanation

First find the amount: n = c × V = 0.200 mol/dm³ × 0.250 dm³ = 0.050 mol. Then m = n × M = 0.050 × 58.5 = 2.93 g.

Question 38Chemical calculations, stoichiometry and quantitative relationships

What volume of 0.500 mol/dm³ hydrochloric acid is required to prepare 100 cm³ of a 0.100 mol/dm³ solution?

  1. 50.0 cm³
  2. 5.0 cm³
  3. 20.0 cm³ Correct answer.
  4. 10.0 cm³

Explanation

Dilution conserves the amount of solute: c₁V₁ = c₂V₂, so V₁ = (0.100 × 100) / 0.500 = 20.0 cm³.

Question 39Chemical calculations, stoichiometry and quantitative relationships

In the reaction 2 H₂ + O₂ → 2 H₂O, how many moles of water are produced when 3 mol of H₂ react completely with excess oxygen?

  1. 3 mol Correct answer.
  2. 2 mol
  3. 1.5 mol
  4. 6 mol

Explanation

The stoichiometric ratio of H₂ to H₂O is 2:2, i.e. 1:1, so 3 mol of H₂ gives 3 mol of H₂O.

Question 40Chemical calculations, stoichiometry and quantitative relationships

How many moles of oxygen are required to burn 4 mol of methane completely? CH₄ + 2 O₂ → CO₂ + 2 H₂O

  1. 4 mol
  2. 6 mol
  3. 2 mol
  4. 8 mol Correct answer.

Explanation

The equation shows that one mole of methane requires two moles of oxygen, so 4 mol of CH₄ needs 4 × 2 = 8 mol of O₂.

Question 41Chemical calculations, stoichiometry and quantitative relationships

What mass of magnesium oxide is formed when 4.8 g of magnesium burns completely in oxygen? (A_r: Mg = 24, O = 16; 2 Mg + O₂ → 2 MgO)

  1. 16.0 g
  2. 2.4 g
  3. 8.0 g Correct answer.
  4. 4.8 g

Explanation

4.8 g Mg is 0.20 mol. The ratio Mg : MgO is 1:1, so 0.20 mol MgO forms; its mass is 0.20 × 40 = 8.0 g.

Question 42Chemical calculations, stoichiometry and quantitative relationships

What volume of carbon dioxide at STP is produced when 10 g of calcium carbonate decomposes completely? CaCO₃ → CaO + CO₂ (M = 100 g/mol, V_m = 22.4 dm³/mol)

  1. 22.4 dm³
  2. 4.48 dm³
  3. 1.12 dm³
  4. 2.24 dm³ Correct answer.

Explanation

10 g CaCO₃ is 0.10 mol, which gives 0.10 mol CO₂. At STP this occupies 0.10 × 22.4 = 2.24 dm³.

Question 43Chemical calculations, stoichiometry and quantitative relationships

A compound contains 40.0 % carbon, 6.7 % hydrogen and 53.3 % oxygen by mass. What is its empirical formula? (A_r: C = 12, H = 1, O = 16)

  1. C₂H₄O
  2. CH₂O Correct answer.
  3. C₂H₆O
  4. CHO

Explanation

Dividing each percentage by the atomic mass gives C: 40/12 = 3.33, H: 6.7/1 = 6.7, O: 53.3/16 = 3.33. Dividing by the smallest (3.33) gives the ratio 1:2:1, so the empirical formula is CH₂O.

Question 44Chemical calculations, stoichiometry and quantitative relationships

A hydrocarbon has the empirical formula CH₂ and a molar mass of 56 g/mol. What is its molecular formula? (M(CH₂) = 14 g/mol)

  1. C₂H₄
  2. C₅H₁₀
  3. C₄H₈ Correct answer.
  4. C₃H₆

Explanation

The ratio of molar mass to empirical formula mass is 56 / 14 = 4, so the molecular formula is (CH₂)₄ = C₄H₈.

Question 45Chemical calculations, stoichiometry and quantitative relationships

In the reaction Zn + 2 HCl → ZnCl₂ + H₂, which substance is the limiting reactant when 0.10 mol Zn reacts with 0.10 mol HCl?

  1. Both react completely
  2. HCl Correct answer.
  3. H₂
  4. Zn

Explanation

0.10 mol Zn would require 0.20 mol HCl, but only 0.10 mol HCl is present. HCl is therefore consumed first and limits the reaction.

Question 46Chemical calculations, stoichiometry and quantitative relationships

What is the concentration of a solution containing 4.0 g of NaOH in 500 cm³ of solution? (M = 40 g/mol)

  1. 0.80 mol/dm³
  2. 0.20 mol/dm³ Correct answer.
  3. 0.10 mol/dm³
  4. 0.40 mol/dm³

Explanation

4.0 g NaOH is 0.10 mol, and the volume is 0.500 dm³. Dividing gives c = 0.10 / 0.500 = 0.20 mol/dm³.

Question 47Chemical calculations, stoichiometry and quantitative relationships

25.0 cm³ of hydrochloric acid is exactly neutralised by 20.0 cm³ of 0.100 mol/dm³ sodium hydroxide. What is the concentration of the acid? HCl + NaOH → NaCl + H₂O

  1. 0.080 mol/dm³ Correct answer.
  2. 0.050 mol/dm³
  3. 0.125 mol/dm³
  4. 0.100 mol/dm³

Explanation

The amount of NaOH is 0.100 × 0.0200 = 0.00200 mol, and the 1:1 ratio means the acid also contains 0.00200 mol. Dividing by 0.0250 dm³ gives 0.080 mol/dm³.

Question 48Chemical calculations, stoichiometry and quantitative relationships

25.0 cm³ of 0.100 mol/dm³ sulfuric acid is neutralised by 0.100 mol/dm³ NaOH. What volume of NaOH is needed? H₂SO₄ + 2 NaOH → Na₂SO₄ + 2 H₂O

  1. 100.0 cm³
  2. 50.0 cm³ Correct answer.
  3. 25.0 cm³
  4. 12.5 cm³

Explanation

0.100 × 0.0250 = 0.00250 mol H₂SO₄ requires 0.00500 mol NaOH because the ratio is 1:2. At 0.100 mol/dm³ this is 0.0500 dm³ = 50.0 cm³.

Question 49Chemical calculations, stoichiometry and quantitative relationships

A 12.5 g sample of an impure carbonate contains 80 % CaCO₃ by mass. What volume of CO₂ at STP is released when the carbonate fully decomposes? CaCO₃ → CaO + CO₂ (M = 100 g/mol, V_m = 22.4 dm³/mol)

  1. 1.12 dm³
  2. 4.48 dm³
  3. 2.24 dm³ Correct answer.
  4. 0.56 dm³

Explanation

The pure CaCO₃ mass is 12.5 × 0.80 = 10.0 g, which is 0.10 mol. This yields 0.10 mol CO₂, occupying 0.10 × 22.4 = 2.24 dm³ at STP.

Question 50Chemical calculations, stoichiometry and quantitative relationships

What is the percentage yield if 6.0 g of product is obtained from a reaction whose theoretical yield is 8.0 g?

  1. 133 %
  2. 70 %
  3. 75 % Correct answer.
  4. 80 %

Explanation

Percentage yield = (actual yield / theoretical yield) × 100 = (6.0 / 8.0) × 100 = 75 %.