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POST UTME ESUT 2025 Chemistry | Objective

Are you preparing for POST UTME ESUT 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

A 2.50 g sample of a metal carbonate is heated to produce a 1.25 g sample of the metal oxide. What is the molar mass of the metal carbonate?

A. 100 g/mol

B. 150 g/mol

Correct C. 200 g/mol

D. 250 g/mol

Correct Answer: C

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Question 2

A solution contains 0.50 M NaCl and 0.25 M CaCl2. What is the concentration of Cl- ions in the solution?

A. 0.375 M

Correct B. 0.500 M

C. 0.625 M

D. 0.750 M

Correct Answer: B

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Question 3

A 10.0 L sample of a gas at 2.00 atm and 25°C is compressed to 5.00 L. What is the final pressure of the gas?

A. 4.00 atm

B. 5.00 atm

Correct C. 6.00 atm

D. 8.00 atm

Correct Answer: C

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Question 4

A 2.00 g sample of a metal is heated in a crucible to produce a 1.50 g sample of the metal oxide. What is the percentage yield of the metal oxide?

A. 75%

Correct B. 80%

C. 85%

D. 90%

Correct Answer: B

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Question 5

A 5.00 L sample of a gas at 3.00 atm and 30°C is heated to 50°C. What is the final pressure of the gas?

A. 3.50 atm

B. 4.00 atm

Correct C. 4.50 atm

D. 5.00 atm

Correct Answer: C

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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, ΔHf(Ca(s)) = 0 kJ/mol.

Correct A. -1206.60 kJ/mol

B. -1206.61 kJ/mol

C. -1206.59 kJ/mol

D. -1206.62 kJ/mol

Correct Answer: A

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Question 7

A 2.50 M solution of NaOH is prepared by dissolving 25.0 g of NaOH in 1.00 L of water. What is the concentration of OH- ions in the solution?

Correct A. 0.0100 M

B. 0.0101 M

C. 0.0102 M

D. 0.0103 M

Correct Answer: A

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Question 8

A 25.0 mL sample of 0.100 M HCl is added to a 50.0 mL sample of 0.100 M NaOH. What is the concentration of the resulting solution?

Correct A. 0.0500 M

B. 0.0501 M

C. 0.0502 M

D. 0.0503 M

Correct Answer: A

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Question 9

A solution contains 0.500 g of KNO3 per 100 mL of solution. What is the molarity of the solution?

Correct A. 0.500 M

B. 0.750 M

C. 1.00 M

D. 1.25 M

Correct Answer: A

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Question 10

A 2.00 L sample of 0.100 M HCl is mixed with a 3.00 L sample of 0.100 M NaOH. What is the concentration of the resulting solution?

Correct A. 0.0500 M

B. 0.0501 M

C. 0.0502 M

D. 0.0503 M

Correct Answer: A

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Question 11

The reaction of sodium (Na) with water (H2O) is highly exothermic. What is the primary product of this reaction?

A. Sodium hydroxide (NaOH)

B. Sodium chloride (NaCl)

Correct C. Hydrogen gas (H2)

D. Sodium oxide (Na2O)

Correct Answer: C

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Question 12

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 13

A sample of a polymer has a molecular weight of 100,000 g/mol. What is the degree of polymerization (DP) of the polymer?

A. 100

B. 1000

Correct C. 10,000

D. 100,000

Correct Answer: C

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Question 14

A redox reaction involves the transfer of electrons from a reducing agent to an oxidizing agent. What is the primary function of the reducing agent in this reaction?

A. To accept electrons

Correct B. To donate electrons

C. To facilitate the reaction

D. To inhibit the reaction

Correct Answer: B

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Question 15

A solution of 0.1 M HCl is titrated with 0.1 M NaOH. What is the pH of the solution after 50 mL of NaOH has been added?

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 16

The reaction of cyclohexane with bromine in the presence of light yields a mixture of 1,2-dibromocyclohexane and 1,4-dibromocyclohexane. What is the major product of this reaction?

A. 1,2-dibromocyclohexane

Correct B. 1,4-dibromocyclohexane

C. cis-1,2-dibromocyclohexane

D. trans-1,2-dibromocyclohexane

Correct Answer: B

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Question 17

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of H2O(l) if the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol and that of O2(g) is 0 kJ/mol?

Correct A. -285.8 kJ/mol

B. -241.8 kJ/mol

C. -393.5 kJ/mol

D. -572.8 kJ/mol

Correct Answer: A

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Question 18

The reaction of sodium nitrite with hydrochloric acid yields sodium chloride and nitrogen gas. What is the balanced chemical equation for this reaction?

A. \( NaNO_2 \( aq \ \) + HCl (aq) \rightarrow NaCl (aq) + NO (g) + H_2O (l) )

Correct B. \( 2NaNO_2 \( aq \ \) + 2HCl (aq) \rightarrow 2NaCl (aq) + N_2 (g) + H_2O (l) )

C. \( NaNO_2 \( aq \ \) + 2HCl (aq) \rightarrow NaCl (aq) + NO_2 (g) + H_2O (l) )

D. \( NaNO_2 \( aq \ \) + HCl (aq) \rightarrow NaCl (aq) + NO (g) + H_2O (l) )

Correct Answer: B

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Question 19

The s\tandard enthalpy of formation of NH3(g) is -45.9 kJ/mol. What is the s\tandard enthalpy of formation of N2(g) if the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol?

Correct A. -72.4 kJ/mol

B. -45.9 kJ/mol

C. 0 kJ/mol

D. 72.4 kJ/mol

Correct Answer: A

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Question 20

The reaction of sodium carbonate with hydrochloric acid yields sodium chloride, water, and carbon dioxide gas. What is the balanced chemical equation for this reaction?

A. \( Na_2CO_3 \( aq \ \) + HCl (aq) \rightarrow NaCl (aq) + H_2O (l) + CO (g) )

Correct B. \( Na_2CO_3 \( aq \ \) + 2HCl (aq) \rightarrow 2NaCl (aq) + H_2O (l) + CO_2 (g) )

C. \( Na_2CO_3 \( aq \ \) + HCl (aq) \rightarrow NaCl (aq) + H_2O (l) + CO_2 (g) )

D. \( Na_2CO_3 \( aq \ \) + 2HCl (aq) \rightarrow 2NaCl (aq) + H_2O (l) + CO (g) )

Correct Answer: B

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Question 21

A sample of a gas at 25°C and 1 atm is compressed to 2 atm. What is the new volume of the gas, assuming ideal gas behavior?

A. 0.5 L

B. 1 L

Correct C. 2 L

D. 4 L

Correct Answer: C

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Question 22

A solution of NaOH is titrated with HCl. The pH of the solution at the equivalence point is 7. What is the concentration of the NaOH solution?

A. 0.1 M

B. 0.5 M

Correct C. 1 M

D. 2 M

Correct Answer: C

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Question 23

A reaction is first-order with respect to the reac\tant A. If the initial concentration of A is 0.1 M and the rate cons\tant is 0.01 min^-1, what is the concentration of A after 10 min?

Correct A. 0.05 M

B. 0.1 M

C. 0.15 M

D. 0.2 M

Correct Answer: A

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Question 24

A mixture of 2.0 g of NaCl and 1.0 g of KCl is dissolved in 100 mL of water. What is the molarity of the solution?

A. 0.1 M

Correct B. 0.2 M

C. 0.3 M

D. 0.4 M

Correct Answer: B

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Question 25

A polymer has a molecular weight of 100,000 g/mol and a degree of polymerization of 500. What is the molar mass of the repeating unit?

A. 100 g/mol

B. 200 g/mol

Correct C. 500 g/mol

D. 1000 g/mol

Correct Answer: C

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