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Chemistry JAMB Questions and Answers 2023 [Free Download]

This is for UTME Candidates looking for Chemistry JAMB Questions and Answers 2023. Especially for those aspiring for Medicine, Pharmacy, Health Sciences, Engineering and other Physical Science courses. Here you will get genuine Chemistry JAMB questions and answers for 2023 set. Your duty now is to read through them as many times as possible and get ready to smash your own Chemistry paper. Proper revision is one of the proven JAMB Success Secrets.

Chemistry JAMB Questions and Answers 2023. Free jamb past questions for revision

What are Chemistry JAMB Questions and Answers 2023

Chemistry JAMB Questions and Answers 2023 are the past questions of Chemistry paper for 2023 UTME, together with their answers.

If you are a candidate preparing to sit for Chemistry in the forthcoming JAMB examination, it is very important that you revise with these past questions.

In so doing, you will know what the set before them saw in the JAMB CBT hall. That would give you an idea of what to expect in your own set because JAMB follows the same pattern in setting their questions. More so, revising these questions several times will boost your confidence and guarantee you a very high score.

Chemistry JAMB Questions and Answers 2023 for Your Revision

On this page, we shall show you the real Chemistry JAMB Questions and Answers taken by the 2023 candidates.

The correct answers to the questions are also provided alongside.

We are providing these past questions to ensure that you have sufficient materials available for your revision. JAMB is a very serious examination. And we understand the role adequate preparation plays for candidates who get very high score in JAMB.

Of course, you know that JAMB gives you 40 questions in Chemistry, to answer within 26 minutes. So it’s important that you prepare very well by reading the content of this page over and over.

In the following sections, you will read the 2023 JAMB Chemistry past questions and their answers. You can use the comments section if you still need clarification over some of the questions. We will give you a more detailed explanation.

Chemistry JAMB Questions and Answers 2023 [Numbers 1 – 10]

1. Which of the following is a mixture?
A. Sodium chloride
B. Sea water
C. Iron filings
D. Granulated sugar

2. Two elements, X and Y, have atomic numbers 8 and 13 respectively. The formula for the possible compound found between X and Y is
A. Y2X3         B. XY2
C. X3Y2         D. X2Y3

3. 3 g of a mixture of CaO and CaCO3 was heated to a constant mass. If 0.44 g of CO2 was liberated, calculate the percentage of CaO in the mixture.
A. 33.3%       B. 50%
C. 66.67%     D. 25%

4. An alkanoic acid has a molecular mass of 88. Its molecular formula is
A. C4H9COOH        B. C5H11COOH
C. C3H5COOH        D. C3H7COOH

5. If the rate of diffusion of oxygen is taken as 1cm3s-1, what will be the rate of diffusion of methane whose relative molecular mass is 16?
A. 2.0         B. 1.8
C. 1.4         D. 1.0

6. An increase in temperature causes an increase in the pressure of a gas in a fixed volume due to an increase in the
A. Number of molecules of the gas
B. Density of the gas molecules
C. Number of collisions between the gas molecules
D. Number of collisions between the gas molecules and the walls of the container

7. In electrolysis, the chemical reaction which takes place at the anode is
A. dissociation     B. hydrolysis
C. oxidation         D. reduction

8. In the electrolysis of brine, it is essential to prevent the mixing of the products because
A. sodium and chlorine readily combine
B. chlorine gives a green coloration
C. chlorine readily recombines with sodium hydroxide
D. sodium hydroxide forms a carbonate in the presence of air and chlorine

9. In what way is equilibrium constant for the forward reaction related to that of the reverse reaction?
A. The two equilibrium constants are identical
B. The product of the two is always greater than one
C. The product of the two is expected to be one
D. The addition of the two is expected to be one

10. When chlorine water is exposed to sunlight, the gas evolved is
A. Cl2         B. O2
C. HCl        D. CO2

Answers to Chemistry Question Number 1 – 10

1.B     2.A     3.C    4.D    5.C
6.D     7.C     8.D   9.C    10.B

Chemistry JAMB Questions and Answers 2023 [Numbers 11 – 20]

11. Two immiscible liquids with different boiling points can be separated by
A. the use of separating funnel
B. evaporation
C. distillation
D. decantation

12. A mixture of CaCl2 and CaCO3 in water can be separated by
A. evaporation      B. sublimation
C. distillation        D. decantation

13. Consider the reaction represented by
xPb(NO3)2 → 2PbO + yNO2 + zO2
What are the values of x, y and z respectively?
A. 2, 6, 3       B. 1, 4, 2
C. 2, 4, 1       D. 2, 4, 2

14. 20 cm3 of H2 mixed and separated with 100 cm3 of air containing 21% O2. Calculate the volume of the residual gases at 110 °C.
A. 31 cm3      B. 11 cm3
C. 90 cm3      D. 110 cm3

15. What is responsible for metallic bonding?
A. Sharing of electrons between the metal atoms
B. Attraction between the atomic nuclei and the cloud of electrons
C. Transfer of electrons from one atom to another
D. Attraction between positive and negative ions

16. 25 cm3 of 1.5 M solution of NaCl are added to 50 cm3 0f 3 M NaCl. The molar concentration of the resulting solution is
A. 2.5 M         B. 3 M
C. 2.25 M       D. 4.5 M

17. A solution of salt formed from HCl and NH3 solutions is
A. acidic         B. basic
C. complex    D. neutral

18. Which of the following elements will burn in excess oxygen to form a product that is neutral to litmus?
A. Carbon      B. Hydrogen
C. Sulphur     D. Sodium

19. A current was passed for 10 mins and 0.2 mole of Cu was deposited. How many grammes of Ag will it deposit? (Cu = 64, Ag = 108)
A. 43.2g     B. 21.6g
C. 10.8g     D. 5.4g

20. Pollution of underground water by metal ions is very likely in a soil that has high
A. acidity
B. alkalinity
C. chloride content
D. nitrate content

Answers to Chemistry Question Number 11 – 20

11.A    12.D    13.C    14.D    15.B
16.A    17.A    18.B    19.A    20.D

Chemistry JAMB Questions and Answers 2023 [Numbers 21 – 30]

21. The presence of NaCl in ice will
A. lower the boiling point of NaCl
B. increase the melting point of NaCl
C. make NaCl impure
d. lower the melting point of ice

22. What are the values of x, y and z in the equation below?
xNH3 + yO2 → zNO + 6H2O
A. 2, 3, 4      B. 4, 5, 4
C. 6, 5, 4      D. 2, 3, 4

23. Calculate the volume of CO2 measured at s.t.p produced on heating 250g of potassium hydrogen trioxocarbonate(IV) strongly. (K = 39, H = 1, C = 12, O = 16)
A. 28 dm3      B. 2.8 dm3
C. 5.6 dm3     D. 11.2 dm3

24. The boiling points of water, ethanol, methylbenzene and butan-2-ol are 373.0K, 351.3K, 383.6K and 372.5K respectively. Which liquid has the highest vapour pressure at 323.0K?
A. Water        B. Methylbenzene
C. Ethanol     D. Butan-2-ol

25. The conclusion from Rutherford’s alpha-scattering experiment is that
A. Atoms are mostly empty space with a small nucleus
B. Emissions from radioactive substances consist of three main components
C. There is a nuclear pull on orbital electrons
D. Electrons are deflected by both magnetic and electric fields

26. Elements P, Q and R have atomic numbers 9, 16 and 20 respectively. Which of them would gain electron(s) during ionic bonding?
A. Q and R        B. P and R
C. P and Q        D. P, Q and R

27. Which of the following has the lowest pH?
A. 5cm3 of M/10 HCl
B. 10cm3 of M/10 HCl
C. 20cm3 of M/8 HCl
D. 15cm3 of M/2 HCl

28. Which of the following is an acid salt?
A. (NH4)2CO3      B. CHCOONa
C. KHSO4            D. MgSO4.7H2O

29. CrO2-7 + 14H+ + 6I → 2Cr3+ + 3I2 + 7H2O
The change in the oxidation number of oxygen in the equation above is
A. 0           B. 1
C. 2           D. 7

30. During the electrolysis of CuSO4 solution using Platinum electrodes, which of the following occurs?
A. Acidity increases at the cathode
B. Oxygen is liberated at the cathode
C. pH decreases at the cathode
D. pH of solution decreases

Answers to Chemistry Question Number 21 – 30

21.D    22.B    23.A     24.C    25.A
26.C    27.D    28.C     29.A    30.D

Chemistry JAMB Questions and Answers 2023 [Numbers 31 – 40]

31. Crystallization is a better method of separation than precipitation because
A. precipitation tends to bring other solutes out of solution
B. crystallization is applicable to all solids
C. precipitation always involves salting-out
D. crystallization can only be done at high temperatures

32. Which of the following is not a chemical change?
A. burning of magnesium
B. rusting of iron
C. action of water on potassium
D. dissolving powdered sulfur in carbon disulfide

33. An important ore of iron contains 72.36% iron and 27.64% oxygen. Determine its empirical formula
A. FeO         B. Fe2O3
C. Fe3O4      D. Fe2O2

34. Which of the following decreases when a given mass of gas is compressed to half its initial volume?
A. average intermolecular distance
B. frequency of collision
C. number of molecules present
D. atomic radius of each particle

35. The densities of two gases X and Y are 2.5gdm-3 and 10.0gdm-3 respectively. What is the rate of diffusion of X relative to Y?
A. 1:2.5      B. 2.5:1
C. 1:2         D. 2:1

36. The properties of elements are periodic functions of their
A. atomic number          B. atomic radius
C. atomic volume           D. mass number

37. Which of the following solutions containing only hydroxyl ions will liberate hydrogen gas when reacted with Mg metals?
A. 1.0×10-5moldm-3          B. 1.0×10-13moldm-3
C. 1.0×10-3moldm-3          D. 1.0×10-2moldm-3

38. In the redox reaction
2Fe2+ + Cl2 → 2Fe3+ + 2Cl
A. Cl2 is reduced because it has lost electrons
B. Cl2 is reduced because its oxidation number has decreased
C. Fe2+ is reduced because it has lost electrons
D. Fe2+ is reduced because it has gained electrons

39. During electrolysis of molten sodium chloride,
A. chlorine atom gains an electron
B. chloride ion gains an electron
C. chloride ion is oxidized
D. sodium ion is oxidized

40. Coffee stains are removed with
A. turpentine          B. ammonia
C. borax in water    D. kerosene

Answers to Chemistry Question Number 31 – 40

31.A    32.D    33.A    34.A     35.D
36.A    37.B    38.B     39.C     40.C

Read Also: 50 JAMB Most Repeated Topics in Chemistry Exams


So here you have the 40 Chemistry JAMB Past Questions for 2023. Read them again and again. Ensure that you get very familiar with each of them such that you can readily recognize them any time. That’s what revision is all about.

Remember that you can ask for more detailed explanation to any of the above questions in case you don’t fully understand it. Don’t be shy, just scroll down and use the comments section. Drop your questions and expect comprehensive answers as soon as possible.

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See you on the next article.

Read Also: Chemistry JAMB Questions and Answers 2024 [Revealed!]

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  1. happy I met this before my exam o. kudos to you sir

  2. why not practise the questions and hope for the best

  3. Haha tomorrow is my day.

  4. Oluwatusin Peter Seyi

    can you please explain how you got 66.67% as %CaO in the mixture in question 3 of the chemistry JAMB question?

    • U can goggle the question and u will see an explanation

    • To calculate the percentage of CaO in the mixture, we need to find the mass of CaCO3 that decomposed to produce the 0.44 g of CO2.

      1 mole of CaCO3 produces 1 mole of CO2, and the molar masses are:
      CaCO3: 40.08 g/mol (Ca) + 12.01 g/mol (C) + 3 * 16.00 g/mol (O) = 100.09 g/mol
      CO2: 12.01 g/mol (C) + 2 * 16.00 g/mol (O) = 44.01 g/mol

      Now, we can calculate the number of moles of CO2 produced:
      0.44 g CO2 / 44.01 g/mol = 0.01 mol CO2

      Since 1 mole of CaCO3 produces 1 mole of CO2, the same amount of moles of CaCO3 decomposed to produce the CO2. Therefore, the mass of CaCO3 that decomposed is 0.01 mol * 100.09 g/mol = 1 g.

      Now, to find the mass of CaO in the mixture, subtract the mass of CaCO3 from the total mass of the mixture:
      Mass of CaO = Total mass – Mass of CaCO3 = 3 g – 1 g = 2 g

      Finally, calculate the percentage of CaO in the mixture:
      Percentage of CaO = (Mass of CaO / Total mass of the mixture) * 100
      Percentage of CaO = (2 g / 3 g) * 100 ≈ 66.67%

      So, the correct answer is C. 66.67%.

  5. Is this wat is going to come abi wetin

  6. is this true please

  7. Is it legit

  8. Is this questions the correct ones and is it truly reliable

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