JAMB Chemistry Past Questions and Answers 2026 (Free CBT Practice Test)

1. What are the separation techniques involved in obtaining pure alum from powdered mixture of alum and sand?

2. In the food processing industry, the separation technique used for analytical purpose is

3. The method suitable for separating suspended particles in a liquid is

4. 18. The purity of common salt (NaCl) can be determined by

5. The mist suitable method for separating a mixture of ethanol and water is?

6. The method suitable for separating suspended particles in liquid is:

7. Common salt (NaCl) is used to preserve foods. Which of the following properties can be used to determine its purity before use?

8. Silica gel, when exposed to air, turns liquid. What kind of substance is it?

9. On exposure to the atmosphere, a hydrated salt loses its water of crystallization to become anhydrous. This phenomenon is referred to as:

10. Which of the following pairs are both substances deliquescent?

11. A solid that absorbs water from the atmosphere and forms an aqueous solution is:

12. What changes sodium hydroxide pellets to liquid?

13. The technique commonly used in the purification of solids is

14. The presence of impurity in a substance will cause the melting point to

15. Which of the following techniques would be used in a food industry?

16. An example of homogenous mixture is

17. Rain water is considered as a mixture because?

1. What is the main difference between empirical and molecular formulae?

2. Fine the empirical formula of a compound 69% carbon, 15.3% hydrogen and 30.7% oxygen. [C=12, H=1, O=16].

3. If 50cm³ of hydrogen is sparked with 75cm³ of oxygen: 2H₂ + O₂ → 2H₂O, the volume of the unreacted oxygen is

4. Which of the following equations is not feasible as written?

1. If pressure (p) of a gas is increased while its temperature (T) remains constant what happens to its volume (v)?

2. Which formula is used to calculate the number of moles using pressure, volume and temperature?

3. A gas expands when heated because:

4. A sample of 5.6g of a gas occupies 2.24dm³ at STP. What is its relative molecular mass?

5. If a gold and silver bar are held together for years and gold particles are later found in the silver, which process has occurred?

6. The only factor that affects the internal energy of an ideal gas is

7. What are the laws that form the general gas equation?

8. Under high pressure, real gases do not obey gas laws because molecules:

9. Gas molecules are said to be perfectly elastic because:

10. A given volume of methane diffuses in 20s. How long will it take the same volume of Sulphur (IV) oxide to diffuse under the same conditions?

11. If 200cm³ of a gas at s.t.p. has a mass of 0.268g, determine its molar mass

12. Which of the following is not a support for the particulate nature of matter?

13. If 93cm3 of SO2 diffuses through a porous partition in 14s, how long will it take the same volume of H2S to diffuse through the same partition, under the same conditions?

14. What volume of which gas will be left unused when 100 cm3 of hydrogen and 40cm3 of oxygen are mixed and sparked in a combustion chamber?

15. Entropy increases in which of the following orders?

1. What is the hybridization of the central atom in methane (CH4)?

2. Which of the following elements has the smallest atomic radius?

3. The electrical conductivity of graphite arises from:

4. Which of the following describes the nature of the bond in the ammonium ion (NH4⁺)?

5. Which of the following bond types involves the transfer of electrons?

6. The hybridization of carbon in ethene is?

7. Which of the following elements has the highest electronegativity?

8. The number of unpaired electrons in a ground – state nitrogen atom is?

9. The bond angle in methane is?

10. Which of the following elements will exhibit the most electronegative character?

11. The bond formed between H2O and H+ to form the hydroxonium H3O+ is:

12. Which of the following sets of elements is arranged in increasing order of first ionization energies?

13. Which of the following decreases from left to right across the period but increases down the group in the periodic table?

14. Which of the following molecules is linear?

15. Which of the following properties is not characteristics of electrovalent compounds?

16. The maximum number of electrons that can be accommodated in the shell having the principal quantum number 3 is?

17. The energy required to remove the most loosely bound electron from a gaseous atom is known as the

18. The alkali metals exhibit similar chemical properties because

19. What is emitted during the disintegration of barium nucleus as shown by the equation: ⁵⁶₁₃₈Ba → ⁵⁴₁₃₄Xe + ?

20. The bond that exists in oxonium ions are

21. The structure of diamond is

22. The electronic configuration of Na⁺ is

23. The bonds in naphthalene molecules are

24. What bond is present in hydrated copper (II) ions?

25. In ammonia molecule, the number of non-bonding electron(s) is/are

26. Which of the following has zero fold degeneracy?

27. The radioactive emission with least ionization power is?

28. The maximum number of electrons that the N shell can accomodate is

1. What is the color obtained when starch iodide paper is introduced into a jar containing chlorine?

2. Which of the following gases can be collected over water?

3. Which of the following are secondary air pollutants?

4. All these are natural air pollutants except

5. Which of the following gases is collected by upward displacement of air?

6. The use of hydrogen gas to fill balloons for both meteorological and other scientific pur[poses is limited by its

1. Which of the following metals react with water at the fastest rate?

2. The addition of charcoal to a filter bed in a town water supply is for the purpose of

3. The purest form of natural water is

4. The characteristic crystalline shape of solid water is due to:

5. The salt responsible for temporary hardness is:

6. Steam changes the color of anhydrous cobalt (II) chloride from:

7. The compound used as 'antifreeze' in car radiators in cold regions of the world is:

8. Water molecules are held together by

9. Which of the following can be used to test for the presence of water in the laboratory?

10. Addition of charcoal in the filter bed for water purification is to

11. The resulting solution when water reacts with chlorine contains?

1. Which of these is not a colligative property?

2. The solubility of a solid in a liquid is increased by

3. If 120cm³ of distilled water is added to 180cm³ of 0.50moldm⁻³ sodium hydroxide solution, the new concentration is?

14. The following are miscible with water except

15. What volume of water will be added to 10dm³ of 2moldm⁻³ to obtain 0.5moldm⁻³ solution?

16. Calculate moles present in 200 cm³ of 1.5 mol dm⁻³ HCl.

17.Determine the solubility of Pb(NO₃)₂. is required to saturate 25cm³ of distilled water at 20^o C. Determine the solubility of the salt at this temperature.

1. Which oxide pollutant causes irritation of eyes, nose and respiratory tract?

2. Which of the following contributes least to the greenhouse effect?

3. An example of a solid-gas mixture is

4. The pollutant that contributes to the depletion of the ozone layer is:

5. The most dangerous gaseous pollutants is?

1. If the pH of a substance is 3, what is the concentration of H3O⁺? A. B. C. D.

2. Which of the following is a suitable drying agent for H2 gas?

3. Which of the following produces effervescence with sodium hydrogen carbonate?

4. Which of the following metals react with water at the fastest rate?

5. The brown ring test is used to detect the presence of

6. The method commonly used in the preparation of insoluble salts is?

7. Which of the following statements is/are true? (i) H₂SO₄ is a strong electrolyte (ii) CH₃COOH is a weak electrolyte (iii) Aluminum conducts electricity (iv) C₆H₁₂O₆ is a non-electrolyte

8. H⁺ + OH⁻ → H₂O; this type of reaction is

9. Which of the following process will result in a chemical change?

19. The method of preparing a salt depends on its

20. What is the colour of phenolphthalein in an acidic solution

21. With which of the following does ammonia react to produce a dense white fume?

1. What colour change occurs when potassium dichromate (K₂Cr₂O₇) reacts with a reducing agent?

2. Which of the following is a redox reaction?

3. In an electrochemical cell, the reducing agent is found:

4. Which compound of chlorine acts both as an oxidizing and reducing agent?

5. The maximum oxidation state of chlorine in its oxoacids is exhibited in:HClO2

6. Rust on the surface of a metal sheet contain

7. Which of the following reactions is redox?

8. Which of the following bleaches by oxidation?

9. The process that converts ethanol to ethanoic acid is

10. Which of the following pairs are oxidizing agents?

11. What is the oxidation number of chromium in K₂Cr₂O₇?

1. In the electrolysis of dilute H2SO4, the gas produced at the anode is?

2. Calculate the volume in dm3 of oxygen evolved at S.T.P. when a current of 5A is passed through acidified water for 772s (molar volume of gas at STP = 22.4 dm3):

3. The above half-cell reaction 2Cl- = Cl2(g) + 2e- occurring at the anode during the electrolysis of dilute ZnCl2 solution is:

4. What current in amperes will deposit 2.7g of aluminum in 2 hours? [Al = 27, F = 96500 C mol-1]

5. The products of the electrolysis of dilute sodium chloride solution with platinum electrodes are

6. A current of 4A was passed through copper (II) tetraoxosulphate (VI) solution for one hour. What mass of copper was deposited? [Cu = 64, F = 96500C]

7. In electroplating steel with chromium, the cathode is

8. What is the anode in the extraction of aluminium and what reaction takes place at the anode?

9. How many coulombs of electricity will be required to deposit 6.11g of silver from a solution of silver salt? [Ag =108, IF =96,500C].

10. In the process of silver – plating metal X

11. What mass of aluminium is deposited when 15A of current is used to electrolyze its molten form for 2hrs, 30mins?

1. 2SO₂(g) + O_2(g) → 2SO_3(g). The standard heats of formation of SO_2(g) and SO3(g) are -297 KJmol⁻¹ and -396 KJmol⁻¹ respectively. The heat change of the reaction is:

2. What is the term for the amount of heat energy required to raise the temperature of a unit mass of a substance by 1^oC?

3. Which of the following is exothermic?

4. 0.92g of ethanol when burned raised the temperature of 50g of water by 28.6K. Calculate the heat of combustion of ethanol. [C = 12, O = 16, H = 1, Specific heat capacity of water = 4.2 Jg-1K-1]

5. For a reaction to occur spontaneously

6. X₂(g) → 2Y + Z(g), ΔH = -ve. What condition would favour the production of X?

1. The rate of chemical reaction can be expressed as:

2. What is the term for the minimum amount of energy required for a chemical reaction to occur?

3. The rate of a chemical reaction is NOT affected by one of these factors:

4. Which of the following will change when a catalyst is added to a chemical reaction?

5. 'The rate of a reaction is proportional to the number of effective collisions occurring per second between the reactants'. This statement is associated with the

6. A catalysis speeds up the rate of a chemical reaction by?

1. The equilibrium constant Kc is affected by:

2. The value of an equilibrium constant Kc is 1.5×10⁵ at 298 K for a certain reaction. What does this indicate about the reaction?

3. What the significance of the equilibrium constant (Kc) in a chemical reaction?

4. In an equilibrium reaction, which of the following conditions indicates that the maximum yield of the product will be obtained?

5. One method of driving the position of equilibrium of an endothermic reaction forward is to:

1. What is the main product formed from the decomposition of ammonium trioxonitrate(V)?

2. Which statement is correct about sulphur trioxide (SO3)?

3. Which of the following nitrogen oxides is a neutral oxide?

4. The chemical formula for laughing gas is:

5. The sulphide used in coating electric fluorescent tubes is:

6. Chlorine, bromine, and iodine resemble each other in that all:

7. What volume of hydrogen gas is produced at s.t.p. when 6.5g of Zinc (Zn = 65) react with excess dilute sulphuric acid?

8. Which of the following will produce nitrogen (IV) oxide and oxygen when strongly heated? i. NaNO₂ ii. KNO₂ iii. Mg(NO₃)₂ iv. Pb(NO₂)₂

9. Helium is preferred to hydrogen in filling balloons because hydrogen is

10 Which of the following is a heavy chemical?

11. When monoclinic sulphur is cooled below its transition temperature, what happens?

12. During the preparation of ethane, it is passed through which of the following to remove impurities?

13. Which of the following gas will burn with a blue colour?

14. Silicon (IV) oxide after melting at about 1500°C forms what when cooled?

15. An example of an acidic oxide is?

16. The gas that is used for the treatment of cancer is?

17. In the preparation of which of the following gasses is kips apparatus used?

1. What is formed when calcium reacts with water?

2. Why is aluminum used in the construction of airplanes?

3. Thermal decomposition of potassium nitrate (KNO3) produces:

4. Which of these metals is used for screening magnetic fields in electrical devices?

5. In the blast furnace, carbon monoxide acts as:

6. Which of the following statements is true of the electrochemical series?

7. A transition metal would be expected to

8. What is the IUPAC name of KMnO₄?

9. Which of the following are ores of iron? i. Haematite ii. Bauxite iii. Magnetite iv. Cassiterite

10. The earthly impurities in iron ore are removed in the blast furnace by the reaction

11. The following alloys contain copper except

12. Which of the following is thermally stable?

13. The substance extensively used in manufacturing photographic chemicals is

14. Which of these metals will liberate hydrogen from steam?

15. What element is common to permalloy, steel and Alnico?

16. Which of the following is common to all metals?

17. Brass is an alloy of copper and

10. The flame used in welding and cutting of metals is?

11. The alloy of aluminuium used in the construction of aircraft is?

1. What is the IUPAC name of the compound C6H5OH?

2. What is the main product formed when an alkene undergoes hydration in the presence of concentrated H2SO4?

3. Acid hydrolysis of maltose produces:

4. How many isomers does C4H10 have?

5. Which of the following compounds is an isomer of but-1-ene?

6. Aldehydes differ from ketones in their:

7. The acidity of carboxylic acids is primarily due to:

8. Which of the following organic compounds will decolorize both bromine water and acidified KMnO4?

9. Methylethanoate reacts with ammonia to yield:

10. Acid hydrolysis of nitriles will yield:

11. How many isomers of C4H9OH will be tertiary alkanol?

12. Which of the following makes oils distinguished from fats?

13. Hydrogenation of Benzene to cyclohexane is called:

14. A hydrocarbon X has a molar mass of 26 and a carbon atom percentage of 92.3%. What is its molecular formula?

15. The functional group of the compound shown (aldehyde structure) is:

16. Which of the following can undergo both addition reaction and substitution reaction?

17. Naming of the organic compound CH3(CH2)4CH2CH2NH2:

18. CHCl3 + Cl2 → HCl + CCl4. The reaction above is an example of:

19. CxHy + 4O2 = 3CO2 + 2H2O. The hydrocarbon, CxHy, in the reaction above is:

20. The repeating unit in natural rubber is:

20. The repeating unit in natural rubber is:

20. The repeating unit in natural rubber is:

21. Fats and oils are classified as?

22. Ethyne undergoes the following reactions except?

22. How many sigma bonds are there in a benzene ring?

23. The formula (CH₃)₃COH is that of a/an

24. 36. What is the molar mass of the alkyne with the formula CxH₁₄? [H =1, C =12]

25. Determine the molecular formula of a compound whose vapour density and empirical formula are 90 and CH₂O respectively

26. Catalytic hydrogenation of oils results in the production of

27. Benzene produces more soot than ethane on burning because benzene

28. Which of the following substances is used for road surfacing?

29. CH₂BrCHClCH₂CH₂CH₂Br — the name of the compound above is

30. The property of butane and propane that makes them suitable for cooking is

31. Which of these is used in the manufacture of cosmetics?

32. Which of the following methods is used to obtain alkanol from alkene?

33. How many isomers does C₂H₄Br₂ have?

34. One mole of sucrose C₁₂H₂₂O₁₁ dehydrated will give how many moles of carbon?

35. The haloalkane used for the preparation of fungicide is

36. When methane is burnt in excess air, it gives

37. Which of this following can be used in making perfumes?

38. Latex is a polymer of

39. Name the compound below (diagram available on paid class)

40. Which of the following decolorize acidified KMnO₄?

41. Ethanol is used in _____ industry

42. An alcohol which does not have the hydroxyl group bounded to the first carbon atom can be classified as?

1. Which of the following is the spontaneous disintegration of unstable atomic nuclei?

2. Which scientist discovered radioactivity?

3. The charge on an alpha particle is:

WAEC Grammar Question

1. Choose the correct option