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POST UTME MADONNA UNIVERSITY 2025 Chemistry | Objective

Are you preparing for POST UTME MADONNA 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 s\tandard enthalpy of formation of CaCO3(s) from the following data: ΔHf(CaO(s)) = -635.09 kJ/mol, ΔHf(CO2(g)) = -393.51 kJ/mol.

Correct A. -1206.60 kJ/mol

B. -1206.60 kJ/mol

C. -1206.60 kJ/mol

D. -1206.60 kJ/mol

Correct Answer: A

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Question 2

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 3

The s\tandard enthalpy of formation of CO2(g) is -393.51 kJ/mol. What is the s\tandard enthalpy of formation of CaCO3(s) if the s\tandard enthalpy of formation of CaO(s) is -635.09 kJ/mol?

Correct A. -1206.60 kJ/mol

B. -1206.60 kJ/mol

C. -1206.60 kJ/mol

D. -1206.60 kJ/mol

Correct Answer: A

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Question 4

A diagram of a cell is shown below. If the concentration of the H+ ions is 0.100 M, what is the concentration of the OH- ions?

A. 0.100 M

Correct B. 0.0100 M

C. 0.00100 M

D. 0.000100 M

Correct Answer: B

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Question 5

The s\tandard enthalpy of formation of CO2(g) is -393.51 kJ/mol. What is the s\tandard enthalpy of formation of CaCO3(s) if the s\tandard enthalpy of formation of CaO(s) is -635.09 kJ/mol?

Correct A. -1206.60 kJ/mol

B. -1206.60 kJ/mol

C. -1206.60 kJ/mol

D. -1206.60 kJ/mol

Correct Answer: A

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Question 6

Determine the s\tandard enthalpy of formation of CaCO3(s) from the following data: ΔHf(CaO(s)) = -635.09 kJ/mol, ΔHf(CO2(g)) = -393.51 kJ/mol.

Correct A. -1206.60 kJ/mol

B. -1206.60 kJ/mol

C. -1206.60 kJ/mol

D. -1206.60 kJ/mol

Correct Answer: A

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Question 7

The s\tandard enthalpy of formation of NH3(g) is -45.9 kJ/mol. Calculate the s\tandard enthalpy of formation of N2H4(l) from the following data: ΔHf(N2(g)) = 0 kJ/mol, ΔHf(H2(g)) = 0 kJ/mol.

Correct A. -85.8 kJ/mol

B. -85.8 kJ/mol

C. -85.8 kJ/mol

D. -85.8 kJ/mol

Correct Answer: A

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Question 8

A 2.50 g sample of an unknown metal carbonate is heated to produce 1.25 g of CO2(g). Calculate the molar mass of the metal carbonate.

Correct A. 100.0 g/mol

B. 100.0 g/mol

C. 100.0 g/mol

D. 100.0 g/mol

Correct Answer: A

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Question 9

A 10.0 mL sample of a 0.100 M solution of CuSO4(aq) is mixed with 20.0 mL of a 0.0500 M solution of NaOH(aq). Calculate the concentration of the resulting solution.

Correct A. 0.0500 M

B. 0.0500 M

C. 0.0500 M

D. 0.0500 M

Correct Answer: A

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Question 10

A 5.00 g sample of an unknown metal is heated in air to produce 2.50 g of metal oxide. Calculate the percentage of metal in the original sample.

Correct A. 50.0%

B. 50.0%

C. 50.0%

D. 50.0%

Correct Answer: A

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Question 11

At 25°C, 1.00 L of an ideal gas at 3.00 atm is compressed to 0.500 L at cons\tant temperature. Calculate the work done on the gas in joules.

A. -1.50 kJ

Correct B. -3.00 kJ

C. -4.50 kJ

D. -6.00 kJ

Correct Answer: B

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Question 12

The reaction 2NO(g) + O2(g) → 2NO2(g) has a rate cons\tant of 0.0500 s^-1 at 25°C. Calculate the rate of reaction when [NO] = 0.100 M and [O2] = 0.0500 M.

A. 1.00 × 10^-3 M s^-1

B. 5.00 × 10^-4 M s^-1

Correct C. 2.50 × 10^-4 M s^-1

D. 1.25 × 10^-4 M s^-1

Correct Answer: C

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Question 13

A 25.0-g sample of a polymer is dissolved in 100.0 mL of a solvent. The solution has a vis\cosity of 0.500 Pa·s. Calculate the molar mass of the polymer.

A. 1.00 × 10^4 g/mol

B. 5.00 × 10^4 g/mol

Correct C. 1.00 × 10^5 g/mol

D. 5.00 × 10^5 g/mol

Correct Answer: C

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Question 14

A 1.00-L sample of a gas at 25°C and 1.00 atm is mixed with a 2.00-L sample of a gas at 25°C and 2.00 atm. Calculate the partial pressure of each gas after mixing.

A. 1.00 atm, 2.00 atm

B. 0.500 atm, 1.00 atm

Correct C. 1.25 atm, 2.25 atm

D. 2.00 atm, 4.00 atm

Correct Answer: C

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Question 15

A 10.0-g sample of a metal is heated to 1000°C and then quenched in water. The resulting solution has a pH of 2.00. Calculate the molar mass of the metal.

A. 50.0 g/mol

B. 100 g/mol

Correct C. 200 g/mol

D. 400 g/mol

Correct Answer: C

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Question 16

Determine the pH of a 0.1 M solution of HCl.

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 17

A 25 mL sample of 0.5 M H2SO4 is titrated with 0.5 M NaOH. Calculate the number of moles of NaOH required to reach the equivalence point.

A. 0.025 mol

Correct B. 0.05 mol

C. 0.075 mol

D. 0.1 mol

Correct Answer: B

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Question 18

The diagram below shows a titration curve. Identify the pH at point X.

A. 2

B. 3

Correct C. 4

D. 5

Correct Answer: C

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Question 19

A sample of nitrogen gas is collected over water at a temperature of 25°C and a pressure of 1 atm. Calculate the partial pressure of nitrogen gas.

A. 0.5 atm

B. 0.75 atm

Correct C. 1 atm

D. 1.25 atm

Correct Answer: C

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Question 20

The diagram below shows a simple apparatus for the electrolysis of water. Identify the function of the anode.

Correct A. To produce oxygen gas

B. To produce hydrogen gas

C. To produce water

D. To produce electricity

Correct Answer: A

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Question 21

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, what is the concentration of the reac\tant after 10 minutes?

A. 0.05 M

B. 0.1 M

C. 0.05 M

Correct D. 0.025 M

Correct Answer: D

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Question 22

A 2.0 M solution of HCl is titrated with 0.5 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 23

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of H2O(g)?

A. -241.8 kJ/mol

B. -393.5 kJ/mol

Correct C. -285.8 kJ/mol

D. -241.8 kJ/mol

Correct Answer: C

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Question 24

A 0.1 M solution of FeCl3 is electrolyzed u\sing a platinum electrode. What is the mass of Fe deposited at the cathode after 2 hours?

A. 0.1 g

Correct B. 0.2 g

C. 0.3 g

D. 0.4 g

Correct Answer: B

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Question 25

A 1.0 M solution of H2SO4 is titrated with 0.5 M NaOH. What is the pH of the solution after 20 mL of NaOH has been added?

A. 1

B. 2

Correct C. 3

D. 4

Correct Answer: C

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