POST UTME ABU 2025 Chemistry | Objective

Are you preparing for POST UTME ABU exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2025 Chemistry (Objective) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1
Determine the s\tandard enthalpy of formation of CO2(g) at 298 K, given that the s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol and the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol.
Correct A. -393.5 kJ/mol
B. -110.5 kJ/mol
C. 0 kJ/mol
D. +393.5 kJ/mol

Correct Answer: A

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Question 2
A 0.1 M solution of HCl is titrated with 0.1 M NaOH. Calculate the pH of the solution after 25 mL of NaOH has been added.
A. 2
Correct B. 3
C. 4
D. 5

Correct Answer: B

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Question 3
A polymer is composed of 80% by mass of a repeating unit with the formula C5H8O2. The density of the polymer is 1.2 g/mL. Calculate the molar mass of the repeating unit.
A. 56 g/mol
Correct B. 72 g/mol
C. 88 g/mol
D. 104 g/mol

Correct Answer: B

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Question 4
A redox reaction involves the oxidation of Fe2+ to Fe3+ and the reduction of MnO4- to Mn2+. Write the balanced equation for the reaction.
Correct A. Fe2+ + MnO4- → Fe3+ + Mn2+
B. Fe2+ + MnO4- → Fe3+ + MnO2
C. Fe2+ + MnO4- → Fe2+ + Mn2+
D. Fe3+ + MnO4- → Fe2+ + Mn2+

Correct Answer: A

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Question 5
A diagram of a titration setup is shown below.
A. The solution in beaker A is acidic.
Correct B. The solution in beaker A is basic.
C. The solution in beaker B is acidic.
D. The solution in beaker B is basic.

Correct Answer: B

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Question 6
A 2.5 L sample of CO2 at 25°C and 1 atm is heated to 50°C. Calculate the new volume of CO2, assuming ideal gas behavior.
A. 3.5 L
Correct B. 4.1 L
C. 5.0 L
D. 6.3 L

Correct Answer: B

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Question 7
A solution of HCl is titrated with NaOH. If 25 mL of 2 M HCl requires 35 mL of 1 M NaOH for neutralization, what is the concentration of HCl?
A. 0.5 M
Correct B. 1.0 M
C. 1.5 M
D. 2.0 M

Correct Answer: B

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Question 8
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of H2O(l) from the following reaction: CO(g) + H2(g) → H2O(l) + C(s).
Correct A. -285.8 kJ/mol
B. -241.8 kJ/mol
C. -393.5 kJ/mol
D. -572.2 kJ/mol

Correct Answer: A

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Question 9
A sample of iron ore contains 70% Fe2O3. If 250 g of the ore is heated in the presence of CO, what is the maximum amount of Fe produced?
A. 150 g
B. 175 g
Correct C. 200 g
D. 225 g

Correct Answer: C

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Question 10
A solution of 0.1 M HCl is titrated with 0.2 M NaOH. If 25 mL of HCl requires 20 mL of NaOH for neutralization, what is the concentration of HCl?
A. 0.2 M
Correct B. 0.3 M
C. 0.4 M
D. 0.5 M

Correct Answer: B

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Question 11
Determine the solubility of AgCl in a 0.1 M solution of NaCl at 25°C. The solubility product cons\tant (Ksp) for AgCl is 1.8 × 10^-10.
A. 1.0 × 10^-5 M
Correct B. 1.5 × 10^-5 M
C. 2.0 × 10^-5 M
D. 3.0 × 10^-5 M

Correct Answer: B

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Question 12
A 2.5 M solution of H2SO4 is electrolyzed u\sing a platinum electrode. If the current is 5.0 A and the electrolysis is carried out for 2.0 hours, calculate the mass of oxygen gas produced at the anode.
A. 0.50 g
B. 1.0 g
Correct C. 1.5 g
D. 2.0 g

Correct Answer: C

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Question 13
The reaction between H2 and O2 is catalyzed by a platinum catalyst. The rate cons\tant (k) for the reaction is 2.5 × 10^-3 s^-1 at 25°C. If the initial concentration of H2 is 0.1 M, calculate the concentration of H2 after 10 minutes.
A. 0.05 M
B. 0.075 M
Correct C. 0.10 M
D. 0.125 M

Correct Answer: C

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Question 14
A 1.0 M solution of NaOH is mixed with a 1.0 M solution of HCl. If the reaction is carried out at 25°C, calculate the pH of the resulting solution.
A. 1.0
Correct B. 2.0
C. 3.0
D. 4.0

Correct Answer: B

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Question 15
A 2.0 M solution of CH3OH is mixed with a 2.0 M solution of H2O. If the reaction is carried out at 25°C, calculate the equilibrium cons\tant (K) for the reaction.
A. 1.0
Correct B. 2.0
C. 3.0
D. 4.0

Correct Answer: B

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Question 16
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. If the pH of the resulting solution is 9.00, what is the volume of NaOH added?
A. 10.0 mL
Correct B. 20.0 mL
C. 25.0 mL
D. 30.0 mL

Correct Answer: B

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Question 17
A solution contains 0.0500 M NaOH and 0.0500 M HCl. What is the pH of the solution?
A. 7.00
Correct B. 7.50
C. 8.00
D. 9.00

Correct Answer: B

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Question 18
A 50.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. If the pH of the resulting solution is 7.00, what is the volume of NaOH added?
A. 10.0 mL
B. 20.0 mL
Correct C. 25.0 mL
D. 30.0 mL

Correct Answer: C

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Question 19
A solution contains 0.0500 M NaOH and 0.0500 M HCl. What is the pH of the solution?
A. 7.00
B. 7.50
Correct C. 8.00
D. 9.00

Correct Answer: C

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Question 20
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. If the pH of the resulting solution is 9.00, what is the volume of NaOH added?
A. 10.0 mL
Correct B. 20.0 mL
C. 25.0 mL
D. 30.0 mL

Correct Answer: B

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