POST UTME LASU 2025 Chemistry | Objective

Are you preparing for POST UTME LASU 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 pH of a 0.1 M solution of HCl in water at 25°C, given that the dissociation cons\tant of HCl is 10^\( -7 \).
A. 1
B. 2
C. 3
Correct D. 4

Correct Answer: D

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Question 2
A diagram of a titration setup is shown below. If 25 mL of 0.1 M NaOH is added to 25 mL of 0.1 M HCl, what is the pH of the resulting solution?
A. 1
Correct B. 2
C. 3
D. 4

Correct Answer: B

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Question 3
A 1.0 L solution contains 0.5 mol of a non-electrolyte solute. What is the mole \fraction of the solute?
Correct A. 0.5
B. 0.25
C. 0.75
D. 0.33

Correct Answer: A

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Question 4
A diagram of a simple black and white chemistry apparatus showing a titration setup is shown below. If 25 mL of 0.1 M NaOH is added to 25 mL of 0.1 M HCl, what is the pH of the resulting solution?
A. 1
Correct B. 2
C. 3
D. 4

Correct Answer: B

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Question 5
A 1.0 L solution contains 0.5 mol of a non-electrolyte solute. What is the mole \fraction of the solute?
Correct A. 0.5
B. 0.25
C. 0.75
D. 0.33

Correct Answer: A

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Question 6
A reaction is said to be at equilibrium when the rates of forward and reverse reactions are equal. What is the name of the law that describes this condition?
Correct A. Le Chatelier's Principle
B. Gibbs Free Energy Equation
C. Equilibrium Cons\tant Expression
D. Rate Law

Correct Answer: A

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Question 7
A solution of 0.1 M HCl is titrated with 0.1 M NaOH. What is the pH of the solution after 25 mL of NaOH has been added?
A. 1
B. 2
Correct C. 3
D. 4

Correct Answer: C

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Question 8
A diagram of a titration setup is shown below.
A. The burette contains the acid.
B. The beaker contains the base.
Correct C. The burette contains the base.
D. The beaker contains the acid.

Correct Answer: C

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Question 9
A reaction is said to be spon\taneous when the Gibbs Free Energy change is negative. What is the name of the equation that describes this condition?
Correct A. ΔG = ΔH - TΔS
B. ΔG = ΔH + TΔS
C. ΔG = -ΔH + TΔS
D. ΔG = ΔH - TΔS

Correct Answer: A

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Question 10
A diagram of a chemical apparatus is shown below.
A. The test tube contains the acid.
B. The burette contains the base.
Correct C. The test tube contains the base.
D. The burette contains the acid.

Correct Answer: C

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Question 11
The rate cons\tant (k) for a first-order reaction is given by the equation: k = Ae^\( -Ea/RT \). If the activation energy (Ea) is 100 kJ/mol, the gas cons\tant (R) is 8.314 J/mol*K, and the temperature (T) is 300 K, what is the value of the rate cons\tant (k) if the pre-exponential factor (A) is 1.0 x 10^10 s^-1?
A. 1.0 x 10^5 s^-1
B. 1.0 x 10^6 s^-1
C. 1.0 x 10^7 s^-1
Correct D. 1.0 x 10^8 s^-1

Correct Answer: D

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Question 12
A solution of 0.1 M NaCl is prepared by dissolving 6.0 g of NaCl in 100 mL of water. What is the concentration of Na+ ions in the solution?
A. 0.01 M
B. 0.05 M
Correct C. 0.1 M
D. 0.5 M

Correct Answer: C

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Question 13
A 2.0 L flask contains 1.0 atm of O2 at 25°C. What is the partial pressure of O2 in the flask?
A. 0.5 atm
Correct B. 1.0 atm
C. 1.5 atm
D. 2.0 atm

Correct Answer: B

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Question 14
A sample of 1.0 g of C6H12O6 is burned in a bomb calorimeter. The heat of combustion is 13.8 kJ/g. What is the total heat of combustion for the sample?
A. 13.8 kJ
B. 27.6 kJ
C. 41.4 kJ
Correct D. 55.2 kJ

Correct Answer: D

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Question 15
A solution of 0.1 M HCl is prepared by dissolving 6.0 g of HCl in 100 mL of water. What is the pH of the solution?
A. 1
B. 2
C. 3
Correct D. 4

Correct Answer: D

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Question 16
A 2.0 L flask contains 1.0 atm of CO2 at 25°C. What is the partial pressure of CO2 in the flask?
A. 0.5 atm
Correct B. 1.0 atm
C. 1.5 atm
D. 2.0 atm

Correct Answer: B

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Question 17
A sample of 1.0 g of C6H12O6 is burned in a bomb calorimeter. The heat of combustion is 13.8 kJ/g. What is the total heat of combustion for the sample?
A. 13.8 kJ
B. 27.6 kJ
C. 41.4 kJ
Correct D. 55.2 kJ

Correct Answer: D

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Question 18
A solution of 0.1 M HCl is prepared by dissolving 6.0 g of HCl in 100 mL of water. What is the pH of the solution?
A. 1
B. 2
C. 3
Correct D. 4

Correct Answer: D

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Question 19
A 2.0 L flask contains 1.0 atm of O2 at 25°C. What is the partial pressure of O2 in the flask?
A. 0.5 atm
B. 1.0 atm
C. 1.5 atm
D. 2.0 atm

Correct Answer: VIEW ANSWER

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Question 20
A sample of a metal oxide, M2O3, has a mass of 25.0 g and a volume of 2.50 cm3. If the density of the oxide is 4.50 g/cm3, calculate the molar mass of the oxide.
A. 150 g/mol
B. 200 g/mol
Correct C. 250 g/mol
D. 300 g/mol

Correct Answer: C

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Question 21
A solution of HCl is prepared by dissolving 25.0 g of HCl in 100.0 cm3 of water. Calculate the concentration of the solution in mol/dm3.
Correct A. 0.25 mol/dm3
B. 0.50 mol/dm3
C. 1.00 mol/dm3
D. 2.00 mol/dm3

Correct Answer: A

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Question 22
A 2.00 M solution of NaOH is prepared by dissolving 40.0 g of NaOH in 1000.0 cm3 of water. Calculate the concentration of the solution in mol/dm3.
A. 0.20 mol/dm3
Correct B. 0.40 mol/dm3
C. 0.80 mol/dm3
D. 1.60 mol/dm3

Correct Answer: B

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Question 23
A sample of a gas has a volume of 2.50 dm3 at a pressure of 1.00 atm and a temperature of 20°C. Calculate the volume of the gas at a pressure of 2.00 atm and a temperature of 30°C.
A. 3.00 dm3
B. 4.00 dm3
Correct C. 5.00 dm3
D. 6.00 dm3

Correct Answer: C

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Question 24
A 2.00 M solution of HCl is prepared by dissolving 40.0 g of HCl in 1000.0 cm3 of water. Calculate the concentration of the solution in mol/dm3.
A. 0.20 mol/dm3
Correct B. 0.40 mol/dm3
C. 0.80 mol/dm3
D. 1.60 mol/dm3

Correct Answer: B

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Question 25
A sample of a metal oxide, M2O3, has a mass of 25.0 g and a volume of 2.50 cm3. If the density of the oxide is 4.50 g/cm3, calculate the molar mass of the oxide.
A. 150 g/mol
B. 200 g/mol
Correct C. 250 g/mol
D. 300 g/mol

Correct Answer: C

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