Chemistry Exam Questions for SS1 Second Term with Answers

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Introduction to Chemistry as a School Subject

Before we venture into Past Chemistry Exam Questions for SS1 Second term, here’s a brief introduction to the subject:

Chemistry is one of the core science subjects taught in secondary schools. It deals with the study of the composition, structure, properties, and changes of matter. In simple terms, Chemistry helps students understand what materials are made of, how they interact, and why they behave the way they do.

As a school subject, Chemistry builds a bridge between Physics and Biology. It explains many natural and industrial processes such as respiration, combustion, rusting, fermentation, and the manufacture of everyday materials like soap, fertilizers, plastics, and drugs.

Through practical experiments and theoretical lessons, students learn important scientific skills such as observation, measurement, problem-solving, and critical thinking. The knowledge of Chemistry also prepares students for careers in Medicine, Engineering, Agriculture, Pharmacy, and Environmental Science.

In summary, Chemistry is the science of substances and their transformations — a subject that helps us understand the world around us and equips students with the foundation for technological and scientific advancement.

Chemistry Exam Questions for SS1 Second Term

Chemistry Exam Questions for SS1 Second Term are divided into two sections:

• Section A
• Section B

The first section, namely, Section A is the objective test, and students are expected to attempt all questions in the section. Section B is the theory part, and students are expected to follow specific instruction and answer the required number of questions.

Note that what you have below are SS1 Chemistry Second Term Exam Past Questions made available to assist students in their revision for 2nd term examinations and also teachers in structuring standard examinations.

SECTION A: Objective Test

Instruction: Answer all questions in this section by choosing from the options lettered A—D. Each question carries equal marks.

1. The chemist who suggested the modern system of representing elements using symbols was
A. Proust              B. Boyle
C. Berzelius          D. Dalton

2. Consider the reaction represented by the following equation: xCH₃OH + yO₂ → 2CO₂ + zH₂O. The values of x, y and z respectively are
A. 2, 3 and 4
B. 2, 4 and 3
C. 1, 2 and 3
D. 1, 3 and 5

3. Which of the following formulae cannot be an empirical formula?
A. CH             B. CH₂
C. P₂O₅          D. N₂O₄

4. The valence electrons in a chloride ion Cl- are
A. 2p electrons only
B. 3s and 3p electrons only
C. 3p and 3d electrons only
D. 3p electrons only

5. What is the empirical formula of a hydrocarbon containing 0.08 mol of carbon and 0.32 mol of hydrogen?
A. CH₂              B. CH₃
C. CH₂              D. C₂H₄

6. The formula of mercury(I)dioxonitrate(III) is
A. HgNO₂             B. HgNO₃
C. Hg₂(NO₂)₂        D. Hg(NO₃)₂

7. An organic compound has empirical formula CH₂. If it’s molar mass is 42g/ mol, what is its molecular firmula? [H = 1.0, C = 12.0] A. C₂H₄                B. C₃H₄
C. C₃H₆                D. C₄H₈

8. Analysis of a hydrocarbon shows that it contains 0.93g of carbon per gram of the compound The mole ratio of carbon to hydrogen in the compound is [H=1, C=12] A. 1:2             B. 1:1
C. 2:1             D. 2:3

9. What is the IUPAC name of the compound represented by the formula NaClO4?
A. Sodium tetraoxochlorate(I)
B. Sodium tetraoxochlorate(IV)
C. Sodium tetraoxochlorate(VI)
D. Sodium tetraoxochlorate(VII)

10. What is the percentage by mass of oxygen in K₂Cr₂O₇? [K₂Cr₂O₇ = 294, O = 16] A. 14.20%           B. 26.53%
C. 35.37%           D. 38.09%

11. If 60g of M combines with 24g of oxygen, what would the empirical formula of the oxide be? [O=16, M=120] A. MO             B. MO₂
C. MO₃           D. MO₄

12. A hydrogen chloride gas reacted with oxygen to yield water and chlorine gas The mole ratio of the hydrogen chloride gas to water is
A. 1:3              B. 2:1
C. 3:1              D. 4:1

13. Which of the following expressions gives the percentage by mass of nitrogen in NH₄NO₃? [N=14, O=16, H=1] A. 14/18 ×100        B. 14/80 × 100
C. 28/80 × 100       D. 28/100 × 80

14. One mole of a compound M(HCO₃)₂ has mass of 162g Calculate the relative atomic mass of M. [H=1, C=12, O=16] A. 122              B. 101
C. 5                  D. 40

15. When a hypothesis is proven within the limit of available evidence, it becomes a
A. theory           B. principle
C. law                D. scope

16. Empirical formula is the
A. simplest formula of a compound
B. molecular formula of a compound
C. chemical formula of a compound
D. structural formula of a compound

17. What volume will 0.5g of hydrogen occupy at stp.? [H=1, molar volume = 22.4dm³] A. 2.24dm³            B. 5.60dm³
C. 11.20dm³          D. 44.8dm³

18. What is the amount of sodium trioxocarbonate (IV) in 5.3g of the compound? (Na₂CO₃ = 106)
A. 0.05            B. 0.10
C. 0.20            D. 0.50

19. What is the amount of hydrogen gas that would be produced if 0.6 mole of hydrochloric acid reacted with excess zinc according to the equation? Zn + 2HCl → ZnCl₂ + H₂
A. 0.1 mole           B. 0.2 mole
C. 0.3 mole           D. 1.0 mole

20. What volume of carbon (IV) oxide is produced when 2.5g of CaCO₃ reacts with acid according to the following equation? CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂ [CaCO₂= 100, molar volume = 22.4dm³] A. 11.2 dm³           B. 5.60dm³
C. 2.24dm³            D. 0.56dm³

21. Calculate the mass of chlorine gas which occupies a volume of 1.12dm³ at stp.[Cl =35.5, molar volume at stp is 22.4dm³] A. 1.80g            B. 3.55g
C. 7.10g            D. 15.5g

22. Mg + 2HCl → MgCl₂ + H₂. From the equation, what mass of hydrogen would be produced if 12.0g of magnesium reacted completely with the acid? (H=1, Mg=24)
A. 1.0g           B. 2.0g
C. 6.0g           D. 12.0g

23. Calculate the mass of sodium hydroxide in 5.00dm³ of a 0.125 mol/dm³ solution [NaOH = 40] A. 0.0156g          B. 0.625g
C. 1.00g              D. 25.0g

24. Given that 1 mole of carbon-12 weighs 12.0g, how many atoms are there in 24.0g magnesium? (C=12, Mg=24, Av. Constant = 6.02 × 10²³)
A. 0.5 × 6.02 × 10²³
B. 1 × 6.02 × 10²³
C. 2 × 6.02 × 10²³
D. 3 × 6.02 × 10²³

25. The mass of 800cm³ of a gas X at stp. is 1.0 g What is the molar mass of X? (Molar volume of gas is 22.4dm³) A. 18.0g mol⁻¹         B. 22.4g mol⁻¹
C. 28.0g mol⁻¹         D. 36.0g mol⁻¹

26. How many moles of carbon (IV) oxide contains 16.0 g of oxygen? (C = 12, O = 16)
A. 0.20 mol          B. 0.25 mol
C. 0.40 mol          D. 0.50 mol

27. How many of oxygen molecule would occupy a volume of 2.24 cm³ at stp? (Molar volume = 22.4dm³, Av. Constant = 6.02 × 10²³)
A. 3.02 × 10²¹         B. 3.02 × 10²²
C. 6.02 × 10²³         D. 6.02 × 10²²

28. How many moles are there in 3.0g of ozone? (O=16)
A. 0.0093         B. 0.0930
C. 0.6250         D. 0.0625

29. An element X forms the following oxides X₂O, XO and XO₂. This phenomenon illustrates the law of
A. conservation of mass
B. definite proportion
C. multiple proportions
D. mass action

30. The law of definite proportion states that
A. chemical compounds are pure because they contain the same elements
B. pure samples of substances are not in the same proportion by mass
C. pure samples of the same compound are in the same proportion by mass
D. matter can neither be created nor destroyed

31. What is the percentage by mass of copper in copper (I) oxide? (O=16, Cu=64)
A. 88.9%          B. 80.0%
C. 66.7%          D. 20.0%

32. In a chemical reaction, the total mass of the products is always equal to that of the reactants This is a statement of the law of
A. definite proportion
B. conservation of mass
C. multiple proportion
D. reciprocal proportions

33. Stoichiometry is based on the law of
A. multiple proportion
B. constant composition
C. conservation of mass
D. conservation of energy

34. A balanced chemical equation is based on the law of
A. periodicity
B. constant composition
C. conservation of matter
D. multiple proportion

35. Which of the following scientists formulated the law of conservation of matter?
A. Lavoisier           B. Dalton
C. Proust               D. Boyle

36. The law of definite proportion was enunciated by
A. J. Proust
B. R. Boyle
C. J. Dalton
D. A. Lavoisier

37. 2.85g of an oxide of copper gave 2.52g of copper on reduction; and 1.90g of another sample of the oxide gave 1.52g of copper on reduction The data above illustrate the law of
A. constant composition
B. conservation of matter
C. multiple proportions
D. reciprocal proportion

38. Chorine atom and chloride ion have the same
A. chemical properties
B. number of protons
C. electron configuration
D. electron charge

39. How many protons are there in a metallic ion (Y²⁺) which has 18 electrons?
A. 20             B. 18
C. 16             D. 14

40. The compound formed by the combination of two elements with a large electronegativity difference is likely to be
A. polar covalent
B. covalent
C. ionic
D. giant molecular

41. A solid substance with high melting and boiling points is likely to be
A. covalent          B. dative
C. ionic                D. non-metal

42. In which of the following compounds does hydrogen form ionic bond?
A. CH₄              B. NH₃
C. NaH             D. HCl

43. Which of the following oxides is ionic?
A. P₂O₅           B. MgO
C. CO₂            D. NO₂

44. When an element Y with atomic number 20 combines with element Z with atomic number 8,
A. a covalent compound, YZ is formed
B. a covalent compound, ZY is formed
C. an ionic compound, YZ is formed
D. an ionic compound, ZY is formed

45. The formula of the compound formed between a trivalent metal, M and a divalent non-metal Y is
A. M₂Y₃            B. M₃Y₂
C. MY₂              D. MY

46. Nucleons are sub-atomic particles, which consist of
A. protons and neutrons
B. neutrons and electrons
C. protons and electrons
D. neutrons, protons and electrons

47. The following gases are diatomic except
A. nitrogen            B. helium
C. hydrogen          D. fluorine

48. An atom with 17 electrons and 18 neutrons has a mass number of
A. 17            B. 18
C. 34            D. 35

49. Scientists whose experiments gave evidence about the nature and structure of the atom include I. J. J. Thompson II. Lord Rutherford III. Le Chatelier IV. Robert Boyle.
A. IV only
B. I and II only
C. III and IV only
D. I, II and III only

50. The Bohr model of the atom proposed the existence of
A. nucleus          B. electrons shell
C. nucleons        D. neutrons

51. The region around the nucleus where electrons can be located is called
A. a spectra        B. an orbital
C. a quanta         D. a field

52. A molecule of phosphorus is
A. diatomic           B. triatomic
C. tetratomic        D. monoatomic

53. Calculate the number of silver atom in pure silver bracelet that has a mass of 35.0 g[ Ag = 108; Av. Constant = 6.02×10²³] A. 1.95 × 10²¹         B. 5.57 × 10²¹
C. 3.25 × 10²²         D. 1.95 × 10²³

54. What is the mass of one atom of carbon? ( C=12, Av. Constant = 6.02× 10²³)
A. 2.00 × 10⁻²³g
B. 3.00 × 10⁻²³g
C. 2.00 × 10²³g
D. 3.01 × 10²³g

55. What is the oxidation number of X in X2O7 ²⁻?
A. +14            B. +12
C. +10            D. +6

56. How many atoms are in 24g of oxygen gas? (O=16.0, NA = 6.02 × 10²³)
A. 9.04 × 10²³         B. 10.02 × 10²³
C. 4.00 × 10²³         D. 9.04×10⁻²³

57. If the difference between the electronegativity of two elements is large, the type of bond formed is
A. ionic           B. covalent
C. dative         D. metallic

58. The following compounds have the same the of bonds except
A. Sodium chloride
B. Potassium chloride
C. Hydrogen chloride
D. Magnesium chloride

59. Electrovalent compounds normally
A. have low melting points
B. have mobile electrons
C. conduct electricity in the solid state
D. dissolve in polar solvent

60. Pairs of outermost electrons which are not used in bonding are
A. lone pairs
B. bond pairs
C. electrovalence electrons
D. Covalent electrons

SECTION B: Essay / Theory

INSTRUCTION – Answer all questions in this section. Write your answers clearly and show working where necessary.

1. Write the balanced equations for the following reactions:
i. Lithium metal burns in chlorine gas to give lithium chloride.
ii. Ethane gas C₂H₆ burns in oxygen to produce carbon (IV) oxides and water.
iii. Mercury (II) oxide is heated to produce mercury and oxygen gas.
iv. Aluminum chloride hydrolyses in water to give aluminum hydroxide and hydrochloric acid.
v. Calcium chloride reacts with sodium trioxocarbonate(IV) to form calcium trioxocarbonate(IV) and sodium chloride.

2a. A gaseous hydrocarbon of mass 7.0g occupies a volume of 2.24dm³ at stp. If the percentage composition by mass of hydrogen is 14.3%, determine its (I) empirical formula (II) Molecular formula [C=12, H=1, Molar volume = 22.4dm³] 2b. Give the IUPAC name of the following compounds:
(I) NaClO₃
(II) CuSO₄. 5H₂O
(III) KMnO₄.
2c. Define relative atomic mass

3a. Define the term mole
3b. Consider the reaction represented by the following equation: 2NaCl + H₂SO₄ → Na₂SO₄ + 2HCl.
If 5.85g of NaCl reacted completely with the acid calculate:
(I) the mass of Na₂SO₄ formed
(II) the volume of HCl gas obtained at stp. (Na = 23, Cl=35.5, O=16, S=32, H=1, Molar volume = 22.4dm³)
3ci. State the law of multiple proportions
3cii. A metal M forms two oxides containing 11.1% and 20.0% of oxygen Show that these figures agree with the law of multiple proportions

4a. Define electrovalent combination
4b. The electronic configuration of the elements X and Y are as follows: X = 1s² 2s² 2p6 3s² 3p6 4s¹ and Y = 1s² 2s² 2p5.
(I) Write the formula of the compound formed when X and Y combine
(II) State four characteristic of the compound formed
(III) State three factors which influence the bond type above

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Answers to Chemistry Exam Questions for SS1 Second Term

Answers to Section A (Objective Test)

The following table gives the correct answers to the objective section of Chemistry exam questions for SS1 Second term. If you are using a mobile device, hold the table and scroll to the right or left for a complete view.

So here you have the answers to the objective section of Chemistry Exam Questions for SS1 Second term. Use the comments section to let me know if you have any questions you would want me to clarify or discuss further.

Answers to Section B (Theory)

1.

i. 2Li + Cl₂ → 2LiCl

ii. 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O

iii. 2HgO → 2Hg + O₂

iv. AlCl₃ + 3H₂O → Al(OH)₃ + 3HCl

v. CaCl₂ + Na₂CO₃ → CaCO₃ + 2NaCl

2a.

Mass of hydrocarbon = 7.0g

Volume occupied at stp = 2.24dm³

Molar volume at stp = 22.4dm³

Number of moles = 2.24 ÷ 22.4 = 0.1 mole

Molar mass = 7.0 ÷ 0.1 = 70g/mol

Percentage of hydrogen = 14.3%

Percentage of carbon = 100 – 14.3 = 85.7%

Assume 100g of compound:

Hydrogen = 14.3g

Carbon = 85.7g

Moles of carbon = 85.7 ÷ 12 = 7.14

Moles of hydrogen = 14.3 ÷ 1 = 14.3

Divide by the smallest:

Carbon = 7.14 ÷ 7.14 = 1

Hydrogen = 14.3 ÷ 7.14 = 2

(I) Empirical formula = CH₂

Empirical formula mass = 12 + 2 = 14

Number of empirical units = 70 ÷ 14 = 5

Molecular formula = (CH₂)₅

(II) Molecular formula = C₅H₁₀

2b.

(I) NaClO₃ = Sodium trioxochlorate(V)

(II) CuSO₄.5H₂O = Copper(II) tetraoxosulphate(VI) pentahydrate

(III) KMnO₄ = Potassium tetraoxomanganate(VII)

2c.

Relative atomic mass is the average mass of an atom of an element compared with one-twelfth of the mass of one atom of carbon-12.

3a.

A mole is the amount of substance that contains 6.02 × 10²³ particles of that substance.

3b.

Equation:

2NaCl + H₂SO₄ → Na₂SO₄ + 2HCl

Molar mass of NaCl = 23 + 35.5 = 58.5g/mol

Number of moles of NaCl = 5.85 ÷ 58.5 = 0.1 mole

From the equation:

2 moles of NaCl produce 1 mole of Na₂SO₄

0.1 mole of NaCl will produce = 0.1 ÷ 2 = 0.05 mole

Molar mass of Na₂SO₄ = (23 × 2) + 32 + (16 × 4)

= 46 + 32 + 64

= 142g/mol

(I) Mass of Na₂SO₄ formed = 0.05 × 142 = 7.1g

From the equation:

2 moles of NaCl produce 2 moles of HCl

Therefore 0.1 mole of NaCl produces 0.1 mole of HCl

Volume of HCl = 0.1 × 22.4

(II) Volume of HCl gas = 2.24dm³

3ci.

The law of multiple proportions states that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other are in simple whole number ratios.

3cii.

First oxide contains 11.1% oxygen.

Therefore metal content = 100 – 11.1 = 88.9%

Ratio of oxygen to metal = 11.1 : 88.9

= 1 : 8

Second oxide contains 20.0% oxygen.

Metal content = 100 – 20 = 80%

Ratio of oxygen to metal = 20 : 80

= 1 : 4

Comparing the oxygen masses combined with the same mass of metal:

1/8 : 1/4

= 1 : 2

This is a simple whole number ratio, therefore the figures agree with the law of multiple proportions.

4a.

Electrovalent combination is the type of chemical bonding formed by the transfer of electrons from one atom to another to form oppositely charged ions.

4b.

(I)

X has one valence electron while Y needs one electron.

X transfers one electron to Y.

Formula of the compound formed = XY

(II) Characteristics of the compound formed

• It has a high melting point.
• It has a high boiling point.
• It conducts electricity when molten or in solution.
• It is soluble in water.

(III) Factors influencing the bond type

• Difference in electronegativity of the atoms.
• Ionization energy of the metal atom.
• Electron affinity of the non-metal atom.

How to Pass Chemistry Exam Questions for SS1 Second Term

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