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POST UTME LEAD CITY UNIVERSITY 2025 Chemistry | Objective

Are you preparing for POST UTME LEAD CITY 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 number of moles of oxygen gas (O2) that will be produced at STP when 2.50 g of potassium chlorate (KClO3) is decomposed according to the equation: 2KClO3(s) → 2KCl(s) + 3O2(g).

A. 0.0500 mol

Correct B. 0.100 mol

C. 0.150 mol

D. 0.200 mol

Correct Answer: B

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Question 2

A 2.5 L flask contains 0.500 mol of an ideal gas at 25°C. If the gas is heated to 50°C at cons\tant volume, what is the new pressure?

A. 1.50 atm

Correct B. 2.00 atm

C. 2.50 atm

D. 3.00 atm

Correct Answer: B

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Question 3

A diagram of a titration setup is shown below. If 25.0 mL of 0.100 M NaOH is required to reach the equivalence point, what is the concentration of the HCl solution?

A. 0.0500 M

Correct B. 0.100 M

C. 0.200 M

D. 0.500 M

Correct Answer: B

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Question 4

A 0.500 L flask contains 0.200 mol of He gas at 27°C. If the gas is compressed to 0.250 L at cons\tant temperature, what is the new pressure?

A. 2.00 atm

Correct B. 2.50 atm

C. 3.00 atm

D. 3.50 atm

Correct Answer: B

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Question 5

A diagram of a simple harmonic motion setup is shown below. If the amplitude of the motion is 5.0 cm and the angular frequency is 2.0 rad/s, what is the maximum acceleration?

A. 10.0 m/s^2

B. 20.0 m/s^2

Correct C. 30.0 m/s^2

D. 40.0 m/s^2

Correct Answer: C

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Question 6

The reaction of aluminum with copper(II) sulfate to form aluminum sulfate and copper is represented by the equation: 2Al(s) + 3CuSO4(aq) → Al2(SO4)3(aq) + 3Cu(s). What is the s\tandard enthalpy change (ΔH°) for this reaction?

Correct A. -1670 kJ/mol

B. -167 kJ/mol

C. 1670 kJ/mol

D. 167 kJ/mol

Correct Answer: A

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Question 7

A sample of nitrogen gas (N2) at 25°C and 1 atm is heated to 100°C. What is the new volume of the gas, assuming it remains at cons\tant pressure?

Correct A. 1.33 L

B. 1.67 L

C. 2.00 L

D. 2.33 L

Correct Answer: A

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Question 8

The s\tandard enthalpy of formation (ΔHf°) for aluminum oxide (Al2O3) is -1675 kJ/mol. What is the s\tandard enthalpy of formation for aluminum (Al) if the s\tandard enthalpy of formation for oxygen gas (O2) is 0 kJ/mol?

A. -1675 kJ/mol

Correct B. -167 kJ/mol

C. 1675 kJ/mol

D. 167 kJ/mol

Correct Answer: B

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Question 9

A 2.50-g sample of sulfur (S) is burned in oxygen gas (O2) to produce sulfur dioxide (SO2). If the reaction is carried out at cons\tant pressure, what is the volume of the SO2 gas produced?

A. 1.33 L

B. 1.67 L

Correct C. 2.00 L

D. 2.33 L

Correct Answer: C

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Question 10

The s\tandard enthalpy of combustion (ΔHc°) for propane (C3H8) is -2220 kJ/mol. What is the s\tandard enthalpy of formation (ΔHf°) for propane if the s\tandard enthalpy of formation for carbon dioxide (CO2) is -393.5 kJ/mol and the s\tandard enthalpy of formation for water (H2O) is -285.8 kJ/mol?

Correct A. -104 kJ/mol

B. -103 kJ/mol

C. -102 kJ/mol

D. -101 kJ/mol

Correct Answer: A

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Question 11

The reaction of nitrogen dioxide with water produces nitric acid and nitric oxide. Write the balanced chemical equation for this reaction, including the correct coefficients.

A. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow 2\text{HNO}_3 + \text{NO}

B. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_3 + 2\text{NO}

Correct C. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow 2\text{HNO}_3 + 2\text{NO}

D. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_3 + \text{NO}_2

Correct Answer: C

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Question 12

A 2.5 M solution of sulfuric acid is diluted to 1 M. What is the volume of the solution that needs to be added to 250 mL of the 2.5 M solution to achieve the desired concentration?

Correct A. 125 mL

B. 250 mL

C. 375 mL

D. 500 mL

Correct Answer: A

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Question 13

The rate cons\tant for a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration after 10 minutes?

A. 0.01 M

Correct B. 0.02 M

C. 0.03 M

D. 0.04 M

Correct Answer: B

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Question 14

A 10 g sample of a subs\tance is found to have a mass of 12 g after being heated in a furnace. What is the percentage increase in mass?

A. 10%

B. 20%

Correct C. 30%

D. 40%

Correct Answer: C

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Question 15

A solution contains 20 g of glu\cose (C6H12O6) per 100 mL. What is the molarity of the solution?

A. 0.5 M

Correct B. 1 M

C. 1.5 M

D. 2 M

Correct Answer: B

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Question 16

Determine the molar mass of a polymer with the following molecular formula: \( C_6H_5CH_2CH_2 \ \)_n).

A. 150 g/mol

B. 300 g/mol

Correct C. 600 g/mol

D. 1200 g/mol

Correct Answer: C

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Question 17

A metal M reacts with chlorine gas to form a white solid product. The reaction is as follows: [ 2M + Cl_2 \rightarrow 2MCl ]. If 2.5 g of M reacts with 1.5 g of Cl_2, what is the percentage yield of the reaction?

A. 50%

B. 60%

Correct C. 70%

D. 80%

Correct Answer: C

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Question 18

A sample of nitrogen gas occupies a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 300 K. What is the number of moles of nitrogen gas present?

A. 0.05 mol

Correct B. 0.1 mol

C. 0.15 mol

D. 0.2 mol

Correct Answer: B

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Question 19

A solution of sodium hydroxide (NaOH) is prepared by dissolving 25 g of NaOH in 100 mL of water. What is the concentration of the solution in terms of molarity?

A. 0.1 M

B. 0.5 M

Correct C. 1 M

D. 2 M

Correct Answer: C

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Question 20

A diagram of a titration setup is shown below. If 25 mL of 0.1 M HCl is required to neutralize 20 mL of NaOH solution, what is the concentration of the NaOH solution?

A. 0.05 M

Correct B. 0.1 M

C. 0.2 M

D. 0.5 M

Correct Answer: B

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Question 21

A 0.1 M solution of a weak base, B, is titrated with 0.1 M HCl. The initial pH of the base is 9.5. If 20 mL of 0.1 M HCl is added to 80 mL of the base, what is the pH of the resulting solution?

A. 7.5

Correct B. 8.5

C. 9.5

D. 10.5

Correct Answer: B

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Question 22

A metal, M, reacts with chlorine gas to form a white solid. The reaction is as follows: M + Cl2 → MX2. If 2.5 g of M is reacted with 5.0 g of Cl2, what is the mass of the white solid formed?

A. 7.5 g

B. 10.0 g

Correct C. 12.5 g

D. 15.0 g

Correct Answer: C

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Question 23

A 1.0 M solution of a weak acid, HA, is titrated with 1.0 M NaOH. The initial pH of the acid is 3.5. If 20 mL of 1.0 M NaOH is added to 80 mL of the acid, what is the pH of the resulting solution?

A. 6.5

B. 7.5

Correct C. 8.5

D. 9.5

Correct Answer: C

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Question 24

A metal, M, reacts with oxygen gas to form a brown solid. The reaction is as follows: 4M + 3O2 → 2MO3. If 2.5 g of M is reacted with 5.0 g of O2, what is the mass of the brown solid formed?

A. 10.0 g

B. 12.5 g

Correct C. 15.0 g

D. 17.5 g

Correct Answer: C

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Question 25

A 1.0 M solution of a weak base, B, is titrated with 1.0 M HCl. The initial pH of the base is 9.5. If 20 mL of 1.0 M HCl is added to 80 mL of the base, what is the pH of the resulting solution?

A. 7.5

Correct B. 8.5

C. 9.5

D. 10.5

Correct Answer: B

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