POST UTME JOSEPH AYO BABALOLA UNIVERSITY 2025 Chemistry | Objective

Are you preparing for POST UTME JOSEPH AYO BABALOLA UNIVERSITY 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.

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Question 1
Determine the major product of the reaction between 2-methylpropene and HCl.
A. 1-chloro-2-methylpropane
B. 2-chloro-2-methylpropane
Correct C. 1-chloro-2-methylpropane and 2-chloro-2-methylpropane
D. 2-chloro-2-methylpropane and 1-chloro-2-methylpropane

Correct Answer: C

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Question 2
The s\tandard Gibbs free energy change for the reaction 2Ag+ + Cu → 2Ag + Cu2+ is -0.46 eV. What is the equilibrium cons\tant for this reaction?
Correct A. 10^\( -0.46 \)
B. 10^(0.46)
C. 10^\( -1.46 \)
D. 10^(1.46)

Correct Answer: A

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Question 3
A 2.5 M solution of a weak acid HA has a pH of 4.5. What is the concentration of the acid?
A. 0.01 M
Correct B. 0.1 M
C. 0.5 M
D. 1 M

Correct Answer: B

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Question 4
A gas at 300 K has a volume of 2.5 L. If the temperature is increased to 400 K, what is the new volume?
A. 3.2 L
Correct B. 4.0 L
C. 4.8 L
D. 5.6 L

Correct Answer: B

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Question 5
A solution containing 0.1 M NaOH and 0.1 M HCl is mixed. What is the pH of the resulting solution?
Correct A. 7
B. 8
C. 9
D. 10

Correct Answer: A

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Question 6
Determine the number of unpaired electrons in the ground state of the chromium ion, Cr3+.
A. 1
Correct B. 2
C. 3
D. 4

Correct Answer: B

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Question 7
A 2.00 M solution of HCl is titrated with 0.500 M NaOH. What is the pH of the solution after 25.0 mL of NaOH has been added?
A. 1.00
B. 2.00
Correct C. 3.00
D. 4.00

Correct Answer: C

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Question 8
The diagram below shows a setup for electrolysis of water. What is the purpose of the U-tube?
A. To collect the gas produced at the cathode
B. To collect the gas produced at the anode
Correct C. To prevent the escape of gas
D. To prevent the entry of air

Correct Answer: C

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Question 9
A 1.00 M solution of NaOH is titrated with 0.500 M HCl. What is the pH of the solution after 50.0 mL of HCl has been added?
A. 1.00
B. 2.00
C. 3.00
Correct D. 4.00

Correct Answer: D

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Question 10
The diagram below shows a setup for electrolysis of water. What is the purpose of the salt bridge?
A. To prevent the mixing of the two solutions
Correct B. To allow the flow of ions between the two solutions
C. To prevent the escape of gas
D. To prevent the entry of air

Correct Answer: B

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Question 11
Determine the pH of a 0.1 M solution of hydrochloric acid (HCl) at 25°C.
A. 1
B. 2
C. 3
Correct D. 4

Correct Answer: D

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Question 12
A 25 mL sample of 0.5 M acetic acid (CH3COOH) is titrated with 1 M sodium hydroxide (NaOH). Calculate the number of moles of NaOH required to reach the equivalence point.
A. 0.025
B. 0.05
C. 0.075
Correct D. 0.1

Correct Answer: D

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Question 13
The rate cons\tant (k) for a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, calculate the concentration after 10 minutes.
A. 0.01
B. 0.02
C. 0.03
Correct D. 0.04

Correct Answer: D

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Question 14
A 2.5 L sample of a 0.2 M solution of sodium carbonate (Na2CO3) is mixed with 1.5 L of a 0.1 M solution of hydrochloric acid (HCl). Calculate the pH of the resulting solution.
A. 1
B. 2
C. 3
Correct D. 4

Correct Answer: D

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Question 15
A 1.0 L sample of a 0.5 M solution of ammonia (NH3) is mixed with 2.0 L of a 0.2 M solution of hydrochloric acid (HCl). Calculate the concentration of the resulting solution.
A. 0.1
B. 0.2
C. 0.3
Correct D. 0.4

Correct Answer: D

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Question 16
Determine the number of moles of sulfur trioxide (SO3) produced when 2.50 g of sulfur (S) is burned in the presence of oxygen (O2) according to the equation: 2S + 3O2 → 2SO3.
A. 0.0500 mol
B. 0.100 mol
Correct C. 0.150 mol
D. 0.200 mol

Correct Answer: C

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Question 17
A 0.500 L sample of a 0.200 M solution of sodium hydroxide (NaOH) is titrated with a 0.500 M solution of hydrochloric acid (HCl). What is the pH of the resulting solution after the reaction is complete?
A. 1.00
Correct B. 2.00
C. 3.00
D. 4.00

Correct Answer: B

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Question 18
A sample of a hydrocarbon \( C_xH_y \) has a molecular weight of 42.0 g/mol. If the density of the sample is 0.800 g/mL, what is the volume (in mL) of 1.00 g of the sample?
A. 25.0 mL
Correct B. 50.0 mL
C. 75.0 mL
D. 100 mL

Correct Answer: B

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Question 19
A 2.00 g sample of a nonmetal (X) is burned in the presence of oxygen (O2) to produce 3.00 g of X2O3. What is the empirical formula of the nonmetal?
Correct A. X2O3
B. XO2
C. X2O
D. XO

Correct Answer: A

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Question 20
A 0.500 M solution of a weak acid (HA) is titrated with a 0.500 M solution of a strong base (NaOH). What is the pH of the resulting solution after the reaction is complete?
A. 1.00
B. 2.00
C. 3.00
Correct D. 4.00

Correct Answer: D

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Question 21
Determine the molar mass of a polymer with the following composition: 60% polyethylene (C2H4), 20% polypropylene (C3H6), and 20% polyvinyl chloride (C2H3Cl).
A. 60 g/mol
Correct B. 80 g/mol
C. 100 g/mol
D. 120 g/mol

Correct Answer: B

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Question 22
A solution contains 0.5 M NaCl. What is the concentration of Cl- ions in the solution?
Correct A. 0.25 M
B. 0.5 M
C. 0.75 M
D. 1.0 M

Correct Answer: A

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Question 23
What is the pH of a solution with a pOH of 4.5?
A. 7.5
B. 8.5
C. 9.5
Correct D. 10.5

Correct Answer: D

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Question 24
A sample of a gas occupies 2.5 L at 25°C. What is the pressure of the gas?
Correct A. 101.3 kPa
B. 202.6 kPa
C. 303.9 kPa
D. 405.2 kPa

Correct Answer: A

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Question 25
A solution contains 0.1 M HCl. What is the concentration of H+ ions in the solution?
A. 0.05 M
Correct B. 0.1 M
C. 0.15 M
D. 0.2 M

Correct Answer: B

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