JAMB Repeated Question for Chemistry (1-50) Question

this post is for JAMB candidates who are preparing to sit for Chemistry in their UTME examination. So I’m going to share the JAMB Repeated Questions in Chemistry with you and tell you few things you need to know about JAMB repeated questions. But beyond showing you the JAMB repeated questions in Chemistry, I will also give you the link to the entire JAMB Chemistry Past Questions and Answers PDF.

JAMB Repeated Questions in Chemistry (1 – 10)
1. Two immiscible liquids with different boiling points can be separated by
A. the use of separating funnel
B. evaporation
C. distillation
D. decantation

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

3. 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

4. 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

5. 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

6. 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

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

8. 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

9. 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. 43.2 g B. 21.6 g
C. 10.8 g D. 5.4 g

10. 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 JAMB Most Repeated Questions in Chemistry (1 – 10)
1.A 2.D 3.C 4.D 5.B
6.A 7.A 8.B 9.A 10.D

JAMB Repeated Questions in Chemistry (11 – 20)
11. What are the values of p, q, r and s respectively in the equation?
pCH4 + qO2 → rCO + sH2O
A. 1, 2, 1, 2 B. 1, 3, 2, 2
C. 2, 3, 2, 4 D. 2, 3, 2, 2

12. KHCO3 is contaminated with K2CO3 as impurity. If 2.5 g of the impure KHCO3 on heating produces 0.224 dm3 of CO2 at s.t.p., calculate the percentage of K2CO3 impurity.
(K = 39, H = 1, C = 12, O = 16)
A. 30% B. 40%
C. 10% D. 20%

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13. The partial pressure of N2 in a container at 50 °C in which there are 0.30 mole of N2 and 1.2 mole of CO2 at a pressure of 2.00 atm is?
A. 0.6 atm B. 0.5 atm
C. 0.4 atm D. 1.6 atm

14. The major reason why chemical reaction occurs among elements is that they have the tendency to
A. attain the nearest noble gas structure
B. become a metal
C. become a non-metal
D. become a noble element

15. Given that the pH of a solution of KOH is 12, what is the concentration of the OH– ions?
A. 0.01 mol/dm3 B. 1 × 10-12 mol/dm3
C. 1 × 10-14 mol/dm3 D. 1 × 10-7 mol/dm3

16. Which of the following salt has a pH less than 7?
A. NaHCO3 B. NH4Cl
C. Na2SO4 D. NaCl

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17. In which of the following reactions does hydrogen peroxide act as a reducing agent?
A. PbO2 + 2HNO3 + H2O2 → Pb(NO3)2 + 2H2O + O2
B. H2S + H2O2 → S + 2H2O
C. PbSO2 + H2O2 → PbSO4 + H2O
D. 2I– + 2H+ + H2O2 → I2 + 2H2O

18. Temporary hardness of water is removed by the use of the following EXCEPT
A. Boiling
B. Use of Ca(OH)2
C. Use of Na2CO3
D. Use of alum

19. Hydration of ions in solution is associated with
A. Liberation of heat B. Absorption of heat
C. Reduction of heat D. Conduction of heat

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20. Which of the following pairs of substances are hygroscopic?
A. CaCl and NaOH
B. CaO and KOH
C. Conc. H2SO4 and MgCl2
D. CuO and CaO

Answers to JAMB Most Repeated Questions in Chemistry (11 – 20)
11.A 12.D 13.B 14.A 15.A
16.A 17.A 18.D 19.A 20.D

JAMB Repeated Questions in Chemistry (21 – 30)
21. 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

22. 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

23. 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

24. 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

25. 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

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

27. 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

28. 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

29. 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

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

Answers to JAMB Most Repeated Questions in Chemistry (21 – 30)
21.A 22.D 23.A 24.A 25.D
26.A 27.B 28.B 29.C 30.C

JAMB Repeated Questions in Chemistry (31 – 40)
31. Addition of water to calcium oxide leads to
A. a physical change
B. a chemical change
C. the formation of a mixture
D. an endothermic reaction

32. 15 g of impure Na2CO3 reacted with excess HNO3. If 0.1 mole of CO2 is produced, what is the percentage purity of the Na2CO3? [Na = 23, C = 12, O = 16] A. 35.3% B. 10.0%
C. 70.66% D. 90.0%

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33. 0.14 g of a hydride of carbon occupies 112.0 cm3 at STP when evaporated. The ratio of carbon to hydrogen is 1:2. The relative molecular formula is
A. C2H4 B. C3H6
C. C4H8 D. C6H12

34. A gas X diffuses twice as fast as a gas Y under the same conditions. If the relative molecular mass of Y is 112, calculate the relative molecular mass of X.
A. 28 B. 14 C. 56 D. 120

35. In the periodic table, what is the property that decreases along the period and increases down the group?
A. Atomic number B. Electron affinity
C. Ionization potential D. Ionic radius

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36. 10 cm3 of 0.1 M HCl are added to 10 cm3 of NaOH solution containing 8 g of NaOH per dm3 of solution. What is the pH of the resulting solution?
A. 11 B. 13 C. 7 D. 8

37. What is the formular of sodium gallate if gallium (Ga) shows an oxidation number of +3?
A. NaGaO3 B. Na2Ga(OH)2
C. NaGa(OH)3 D. NaGa(OH)4

38. The mass of Ag deposited when a current of 10 A is passed through a solution of silver salt for 4830 secs is [Ag = 108, 1F = 96500C] A. 54.0 g B. 27.0 g
C. 13.5 g D. 108.0 g

39. The solubility of alkanols in water is due to
A. their covalent nature
B. hydrogen bond
C. their low boiling point
D. their ionic character

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40. If a reaction is exothermic and there is a great disorder, it means
A. the reaction is in a state of equilibrium
B. there will be a large increase in free energy
C. there will be a large decrease in free energy
D. the reaction is static

Answers to JAMB Most Repeated Questions in Chemistry (31 – 40)
31.B 32.C 33.A 34.A 35.D
36.A 37.D 38.A 39.B 40.C

JAMB Most Repeated Questions in Chemistry (41 – 50)
41. 2SO2(g) + O2(g) → 2SO3(g) ΔH = -395.7kJmol-1
In the reaction above, the concentration of SO3(g) can be increased by
A. decreasing the pressure
B. decreasing the temperature
C. increasing the temperature
D. the addition of catalyst

42. Which of the following compounds is a normal salt?
A. Na2CO3 B. NaHSO4
C. NaHCO3 D. NaHS

43. Which of the following ions can be used as an oxidizing agent?
A. F– B. Fe3+
C. Au3+ D. Ca2+

44. CO(g) + H2O(g) → CO2(g) + H2(g)
Calculate the standard heat change of the reaction above if the standard enthalpies of formation of CO2(g), H2O(g) and CO(g) in KJ mol-1 are -394, -242 and -110 respectively.
A. +262 KJ mol-1 B. -262 KJ mol-1
C. +42 KJ mol-1 D. -42 KJ mol-1

45. CH3CH2CL + KCN → CH3CH2CN + KCL
In the reaction above, the cyanide is
A. nucleophilic B. electrophilic
C. hydrophilic D. hydrophobic

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46. The bleaching action of chlorine gas is effective due to the presence of
A. oxygen B. hydrogen chloride
C. water C. air

47. Which of the following pairs of substances will react further with oxygen to form a higher oxide?
A. SO2 and NO B. CO2 and H2O
C. CO and CO2 D. NO and H2O

48. The salt formed between citric acid and sodium hydroxide in solution will be
A. acidic B. neutral
C. basic D. amphoteric

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49. On exposure to the atmosphere, a hydrated salt loses its water of crystallization to become anhydrous. This phenomenon is referred to as
A. deliquescent B. hygroscopy
C. hydrolysis D. efflorescence

50. Vulcanization involves the removal of
A. a double bond B. the single bond
C. a polymer D. a monomer