Chemistry Mock 2024

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Chemistry Mock 2024

Question 1 of 50

A sodium atom has atomic number 11 and mass number 23. How many neutrons does it have?

A. 11 B. 12 C. 23 D. 34

Question 2 of 50

What is the electron configuration of magnesium (atomic number 12)?

A. 8, 2, 2 B. 2, 10 C. 2, 8, 1, 1 D. 2, 8, 2

Question 3 of 50

Which particle has a relative charge of −1 and almost no mass?

A. proton B. neutron C. electron D. nucleus

Question 4 of 50

What volume does 1 mol of any gas occupy at s.t.p.?

A. 6.02 dm³ B. 24.0 cm³ C. 1 dm³ D. 22.4 dm³

Question 5 of 50

What is the relative formula mass of calcium carbonate, CaCO₃? (Ca = 40, C = 12, O = 16)

A. 68 B. 84 C. 100 D. 116

Question 6 of 50

Iodine crystals change straight from solid to vapour on heating. This is

A. evaporation B. sublimation C. condensation D. melting

Question 7 of 50

Which element has the highest electronegativity?

A. oxygen B. chlorine C. fluorine D. sodium

Question 8 of 50

Sodium chloride is held together by

A. hydrogen bonds B. covalent bonds C. metallic bonds D. ionic bonds

Question 9 of 50

A covalent bond is formed when atoms

A. lose protons B. transfer electrons C. share a pair of electrons D. gain neutrons

Question 10 of 50

The functional group –OH is found in

A. alkanoic acids only B. alkanes C. alkenes D. alkanols (alcohols)

Question 11 of 50

The –COOH group is the functional group of

A. alkanols B. esters C. alkanoic (carboxylic) acids D. ketones

Question 12 of 50

What is the general formula of the alkanes?

A. CₙH₂ₙ₊₁OH B. CₙH₂ₙ C. CₙH₂ₙ₋₂ D. CₙH₂ₙ₊₂

Question 13 of 50

Acid rain is mainly caused by

A. oxygen and nitrogen B. water vapour C. carbon monoxide only D. sulphur dioxide and oxides of nitrogen

Question 14 of 50

Chlorine is 75% chlorine-35 and 25% chlorine-37. What is its relative atomic mass?

A. 36 B. 35.5 C. 35 D. 37

Question 15 of 50

How many moles are in 4.4 g of carbon dioxide? (C = 12, O = 16)

A. 10 mol B. 1 mol C. 0.44 mol D. 0.1 mol

Question 16 of 50

How many molecules are in 0.5 mol of water? (Avogadro's constant = 6.02 × 10²³ mol⁻¹)

A. 6.02 × 10²³ B. 3.01 × 10²³ C. 1.20 × 10²⁴ D. 9.0 × 10²³

Question 17 of 50

What is the mass of 0.25 mol of sodium hydroxide, NaOH? (Na = 23, O = 16, H = 1)

A. 4 g B. 40 g C. 160 g D. 10 g

Question 18 of 50

In the balanced equation N₂ + 3H₂ → 2NH₃, how many moles of hydrogen react with 2 mol of nitrogen?

A. 3 mol B. 6 mol C. 2 mol D. 4 mol

Question 19 of 50

CH₄ + 2O₂ → CO₂ + 2H₂O. How many moles of oxygen are needed to burn 3 mol of methane completely?

A. 3 mol B. 6 mol C. 2 mol D. 1.5 mol

Question 20 of 50

Sweating cools the body because

A. water conducts heat into the body B. sweat is cold C. sweat blocks sunlight D. evaporation takes heat energy from the skin

Question 21 of 50

A gas occupies 2 dm³ at 300 K. At constant pressure, what is its volume at 600 K?

A. 1 dm³ B. 4 dm³ C. 2 dm³ D. 6 dm³

Question 22 of 50

Down Group 1, the reactivity of the alkali metals

A. decreases B. increases C. stays constant D. drops to zero

Question 23 of 50

The energy needed to remove one mole of electrons from one mole of gaseous atoms is the

A. electron affinity B. first ionisation energy C. lattice energy D. electronegativity

Question 24 of 50

The bond formed when both shared electrons come from one atom, as in NH₄⁺, is

A. a hydrogen bond B. an ionic bond C. a metallic bond D. a dative (coordinate) bond

Question 25 of 50

Metallic bonding is best described as

A. transfer of electrons to non-metals B. shared pairs between two atoms C. positive ions in a sea of delocalised electrons D. weak attraction between molecules

Question 26 of 50

Water has an unusually high boiling point for its size because of

A. its low mass B. ionic bonding C. metallic bonding D. hydrogen bonding between molecules

Question 27 of 50

The weak forces between non-polar molecules such as iodine are

A. covalent bonds B. ionic bonds C. van der Waals (dispersion) forces D. hydrogen bonds

Question 28 of 50

Hydrogen bonding occurs between molecules in which hydrogen is bonded to

A. metals B. C C. Cl only D. N, O or F

Question 29 of 50

An organic compound decolourises bromine water. This shows that it

A. is a salt B. is an alkane C. contains a C=C double bond (is unsaturated) D. contains no carbon

Question 30 of 50

The formula of aluminium sulphate is

A. AlSO₄ B. Al₂(SO₄)₃ C. Al₃(SO₄)₂ D. Al(SO₄)₂

Question 31 of 50

The boiling point of HF is higher than HCl mainly because of

A. metallic bonding B. greater mass of HF C. ionic bonding D. hydrogen bonding in HF

Question 32 of 50

The enthalpy of neutralisation of a strong acid and strong base is about

A. 0 kJ/mol B. +57 kJ/mol C. −570 kJ/mol D. −57 kJ/mol

Question 33 of 50

For H₂ + I₂ ⇌ 2HI, increasing the pressure

A. shifts it left B. shifts it right C. has no effect on the position of equilibrium D. stops the reaction

Question 34 of 50

The pH of a 0.001 mol/dm³ HCl solution is

A. 3 B. 1 C. 0.001 D. 11

Question 35 of 50

The oxidation number of chromium in K₂Cr₂O₇ is

A. +6 B. +7 C. +3 D. +12

Question 36 of 50

What mass of sodium contains the same number of atoms as 6 g of carbon? (Na = 23, C = 12)

A. 23 g B. 11.5 g C. 6 g D. 46 g

Question 37 of 50

Balance: Al + O₂ → Al₂O₃. The coefficients are

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

Question 38 of 50

A compound has empirical formula CH₂ and relative molecular mass 56. Its molecular formula is

A. C₅H₁₀ B. C₂H₄ C. C₃H₆ D. C₄H₈

Question 39 of 50

According to Graham's law, the rate of diffusion of a gas is

A. directly proportional to its mass B. inversely proportional to the square root of its molar mass C. independent of mass D. proportional to pressure only

Question 40 of 50

Electron affinity is the energy change when

A. an atom loses an electron B. an atom gains an electron C. bonds break D. atoms combine

Question 41 of 50

The number of lone pairs on the oxygen atom in water is

A. 0 B. 1 C. 2 D. 3

Question 42 of 50

Hess's law states that the enthalpy change of a reaction

A. depends on time B. depends on the catalyst C. is always negative D. is independent of the route taken

Question 43 of 50

According to Hund's rule, electrons fill degenerate orbitals

A. randomly B. in pairs first C. singly with parallel spins before pairing D. only in s orbitals

Question 44 of 50

How many molecules are in 3.6 g of water? (H₂O = 18; L = 6.02 × 10²³)

A. 2.17 × 10²⁴ B. 6.02 × 10²³ C. 3.6 × 10²³ D. 1.20 × 10²³

Question 45 of 50

Hydrogen (M = 2) diffuses how many times faster than oxygen (M = 32)?

A. 2 B. 16 C. 4 D. 8

Question 46 of 50

Which element has the highest first ionisation energy?

A. fluorine B. hydrogen C. neon D. helium

Question 47 of 50

Which molecule has a trigonal planar shape?

A. CH₄ B. NH₃ C. H₂O D. BF₃

Question 48 of 50

A hydrocarbon contains 85.7% carbon by mass. Its empirical formula is

A. CH₃ B. CH₂ C. CH D. C₂H₃

Question 49 of 50

The functional group C=O in an aldehyde is found

A. attached to oxygen B. in the middle of the chain C. at the end of the carbon chain D. in a ring only

Question 50 of 50

When 50 cm³ of 1 M HCl reacts with 50 cm³ of 1 M NaOH, the temperature rises by 6.8 °C. The heat released is about (c = 4.2 J/g K; density 1 g/cm³)

A. 1,428 J B. 2,856 J C. 28,560 J D. 340 J

Questions written by OtisamLMS in the style of the WASSCE. They are not WAEC past questions.