JAMB Chemistry questions: Chemical combination

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

All topics Acids, bases and salts · 32 Air · 21 Atomic structure and bonding · 33 Chemical combination · 31 Chemical equilibrium · 21 Chemistry and industry · 18 Electrolysis · 22 Energy changes · 22 Environmental pollution · 17 Kinetic theory of matter and gas laws · 27 Metals and their compounds · 24 Non-metals and their compounds · 23 Organic compounds · 43 Oxidation and reduction · 22 Rates of chemical reaction · 22 Separation of mixtures and purification · 24 Solubility · 20 Water · 21

Question 1· Chemical combination· JAMB
What mass of oxygen combines with 4 g of hydrogen to form water? (H = 1, O = 16)
Explanation and discussion
Question 2· Chemical combination· JAMB
Find the percentage by mass of nitrogen in NH₄NO₃. (N = 14, H = 1, O = 16)
Explanation and discussion
Question 3· Chemical combination· JAMB
In the reaction 2KClO₃ → 2KCl + 3O₂, how many moles of oxygen are produced from 2 mol of KClO₃?
Explanation and discussion
Question 4· Chemical combination· JAMB
How many molecules are in 4.4 g of carbon(IV) oxide? [C = 12, O = 16, L = 6.0 × 10²³]
Explanation and discussion
Question 5· Chemical combination· JAMB
The law of definite proportions states that
Explanation and discussion
Question 6· Chemical combination· JAMB
How many molecules are in 2 mol of nitrogen gas? (Avogadro's constant = 6.02 × 10²³ mol⁻¹)
Explanation and discussion
Question 7· Chemical combination· JAMB
What mass of sodium hydroxide is needed to prepare 250 cm³ of a 0.2 mol/dm³ solution? [Na = 23, O = 16, H = 1]
Explanation and discussion
Question 8· Chemical combination· JAMB
What mass of carbon(IV) oxide is produced when 6 g of carbon burns completely in oxygen? (C = 12, O = 16)
Explanation and discussion
Question 9· Chemical combination· JAMB
What mass of sodium chloride is formed when 46 g of sodium reacts completely with chlorine? (Na = 23, Cl = 35.5)
Explanation and discussion
Question 10· Chemical combination· JAMB
What is the mass of 22.4 dm³ of carbon(IV) oxide at s.t.p.? (C = 12, O = 16)
Explanation and discussion
Question 11· Chemical combination· JAMB
Gay-Lussac's law states that gases react in volumes that are
Explanation and discussion
Question 12· Chemical combination· JAMB
How many moles of oxygen atoms are in 0.5 mol of carbon(IV) oxide?
Explanation and discussion
Question 13· Chemical combination· JAMB
How many moles of oxygen atoms are present in 0.5 mol of CaCO₃?
Explanation and discussion
Question 14· Chemical combination· JAMB
In the balanced equation aAl + bO₂ → cAl₂O₃, the values of a, b and c are
Explanation and discussion
Question 15· 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 16· 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 17· Chemical combination· JAMB
The law of multiple proportions is illustrated by
Explanation and discussion
Question 18· 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 19· 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 20· 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

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JAMB Chemistry questions: Chemical combination

What mass of oxygen combines with 4 g of hydrogen to form water? (H = 1, O = 16)

Find the percentage by mass of nitrogen in NH₄NO₃. (N = 14, H = 1, O = 16)

In the reaction 2KClO₃ → 2KCl + 3O₂, how many moles of oxygen are produced from 2 mol of KClO₃?

How many molecules are in 4.4 g of carbon(IV) oxide? [C = 12, O = 16, L = 6.0 × 10²³]

The law of definite proportions states that

How many molecules are in 2 mol of nitrogen gas? (Avogadro's constant = 6.02 × 10²³ mol⁻¹)

What mass of sodium hydroxide is needed to prepare 250 cm³ of a 0.2 mol/dm³ solution? [Na = 23, O = 16, H = 1]

What mass of carbon(IV) oxide is produced when 6 g of carbon burns completely in oxygen? (C = 12, O = 16)

What mass of sodium chloride is formed when 46 g of sodium reacts completely with chlorine? (Na = 23, Cl = 35.5)

What is the mass of 22.4 dm³ of carbon(IV) oxide at s.t.p.? (C = 12, O = 16)

Gay-Lussac's law states that gases react in volumes that are

How many moles of oxygen atoms are in 0.5 mol of carbon(IV) oxide?

How many moles of oxygen atoms are present in 0.5 mol of CaCO₃?

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

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)

The law of multiple proportions is illustrated by

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)

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?