JAMB and WAEC Chemistry questions

800 questions with answers and explanations. Tap an option to check yourself.

All topics Acids, bases and salts · 58 Air · 37 Atomic structure and bonding · 59 Chemical combination · 58 Chemical equilibrium · 37 Chemistry and industry · 35 Electrolysis · 41 Energy changes · 38 Environmental pollution · 32 Kinetic theory of matter and gas laws · 45 Metals and their compounds · 47 Non-metals and their compounds · 45 Organic compounds · 72 Oxidation and reduction · 41 Rates of chemical reaction · 38 Separation of mixtures and purification · 42 Solubility · 36 Water · 39

Question 181· Chemical combination· WAEC
A compound contains 40% carbon, 6.7% hydrogen and 53.3% oxygen by mass. Find its empirical formula. [C = 12, H = 1, O = 16]
Explanation and discussion
Question 182· Chemical combination· WAEC
The relative molecular mass of CO₂ is (C = 12, O = 16)
Explanation and discussion
Question 183· Chemical combination· JAMB
In the balanced equation aAl + bO₂ → cAl₂O₃, the values of a, b and c are
Explanation and discussion
Question 184· Chemical combination· WAEC
The volume of 2 mol of an ideal gas at s.t.p. is
Explanation and discussion
Question 185· Chemical combination· WAEC
The percentage of water of crystallisation in CuSO₄·5H₂O (Cu = 64, S = 32, O = 16, H = 1) is
Explanation and discussion
Question 186· Chemical combination· JAMB
What volume of 0.1 mol/dm³ hydrochloric acid is needed to make 250 cm³ of 0.02 mol/dm³ acid?
Explanation and discussion
Question 187· Chemical combination· JAMB
4 g of sodium hydroxide is dissolved in water to make 500 cm³ of solution. Find its concentration. (Na = 23, O = 16, H = 1)
Explanation and discussion
Question 188· Chemical combination· WAEC
Avogadro's number of particles is
Explanation and discussion
Question 189· Chemical combination· JAMB
The law of multiple proportions is illustrated by
Explanation and discussion
Question 190· Chemical combination· WAEC
How many atoms are present in 0.5 mol of sulphur? [L = 6.02 × 10²³]
Explanation and discussion
Question 191· Chemical combination· JAMB
The empirical formula of a compound containing 40% carbon, 6.7% hydrogen and 53.3% oxygen by mass is: (C = 12, H = 1, O = 16)
Explanation and discussion
Question 192· Chemical combination· JAMB
Find the percentage by mass of water of crystallisation in CuSO₄·5H₂O. (Cu = 64, S = 32, O = 16, H = 1)
Explanation and discussion
Question 193· Chemical combination· WAEC
The formula of calcium chloride is
Explanation and discussion
Question 194· Chemical combination· JAMB
In the reaction 2H₂(g) + O₂(g) → 2H₂O(l), what volume of oxygen reacts completely with 20 cm³ of hydrogen at the same temperature and pressure?
Explanation and discussion
Question 195· Chemical combination· WAEC
What mass of calcium oxide is formed by heating 50 g of calcium trioxocarbonate(IV) to constant mass? [Ca = 40, C = 12, O = 16]
Explanation and discussion
Question 196· Chemical combination· WAEC
What is the relative molecular mass of CO₂? (C = 12, O = 16)
Explanation and discussion
Question 197· Chemical combination· JAMB
Find the mass of 3.01 × 10²³ atoms of sodium. (Na = 23; Avogadro's constant = 6.02 × 10²³ mol⁻¹)
Explanation and discussion
Question 198· Chemical combination· JAMB
0.5 g of a gas occupies 280 cm³ at s.t.p. Find its molar mass. [molar volume = 22.4 dm³]
Explanation and discussion
Question 199· Chemical combination· JAMB
How many moles are in 11 g of carbon(IV) oxide? (C = 12, O = 16)
Explanation and discussion
Question 200· Chemical combination· JAMB
How many molecules are in 0.5 mol of water? (Avogadro's constant = 6.02 × 10²³ mol⁻¹)
Explanation and discussion

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JAMB and WAEC Chemistry questions

A compound contains 40% carbon, 6.7% hydrogen and 53.3% oxygen by mass. Find its empirical formula. [C = 12, H = 1, O = 16]

The relative molecular mass of CO₂ is (C = 12, O = 16)

In the balanced equation aAl + bO₂ → cAl₂O₃, the values of a, b and c are

The volume of 2 mol of an ideal gas at s.t.p. is

The percentage of water of crystallisation in CuSO₄·5H₂O (Cu = 64, S = 32, O = 16, H = 1) is

What volume of 0.1 mol/dm³ hydrochloric acid is needed to make 250 cm³ of 0.02 mol/dm³ acid?

4 g of sodium hydroxide is dissolved in water to make 500 cm³ of solution. Find its concentration. (Na = 23, O = 16, H = 1)

Avogadro's number of particles is

The law of multiple proportions is illustrated by

How many atoms are present in 0.5 mol of sulphur? [L = 6.02 × 10²³]

The empirical formula of a compound containing 40% carbon, 6.7% hydrogen and 53.3% oxygen by mass is: (C = 12, H = 1, O = 16)

Find the percentage by mass of water of crystallisation in CuSO₄·5H₂O. (Cu = 64, S = 32, O = 16, H = 1)

The formula of calcium chloride is

In the reaction 2H₂(g) + O₂(g) → 2H₂O(l), what volume of oxygen reacts completely with 20 cm³ of hydrogen at the same temperature and pressure?

What mass of calcium oxide is formed by heating 50 g of calcium trioxocarbonate(IV) to constant mass? [Ca = 40, C = 12, O = 16]

What is the relative molecular mass of CO₂? (C = 12, O = 16)

Find the mass of 3.01 × 10²³ atoms of sodium. (Na = 23; Avogadro's constant = 6.02 × 10²³ mol⁻¹)

0.5 g of a gas occupies 280 cm³ at s.t.p. Find its molar mass. [molar volume = 22.4 dm³]

How many moles are in 11 g of carbon(IV) oxide? (C = 12, O = 16)

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