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POST UTME LAUTECH 2025 Chemistry | Objective

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Question 1

A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. The pH of the resulting solution is 7.00. What is the number of moles of NaOH added?

A. 0.0025 mol

Correct B. 0.0050 mol

C. 0.0075 mol

D. 0.0100 mol

Correct Answer: B

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Question 2

A 2.50 g sample of a polymer is dissolved in 100.0 mL of a solvent. The resulting solution has a vis\cosity of 1.25 cP. What is the molar mass of the polymer?

A. 5000 g/mol

B. 10000 g/mol

Correct C. 15000 g/mol

D. 20000 g/mol

Correct Answer: C

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Question 3

A 50.0 mL sample of a 0.100 M solution of Fe2+ is mixed with 50.0 mL of a 0.100 M solution of MnO4-. What is the resulting concentration of Fe3+?

A. 0.0500 M

B. 0.0750 M

Correct C. 0.100 M

D. 0.125 M

Correct Answer: C

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Question 4

A 100.0 mL sample of a 0.100 M solution of HCl is titrated with a 0.100 M solution of NaOH. The pH of the resulting solution is 7.00. What is the number of moles of NaOH added?

A. 0.0025 mol

Correct B. 0.0050 mol

C. 0.0075 mol

D. 0.0100 mol

Correct Answer: B

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Question 5

A 2.50 g sample of a polymer is dissolved in 100.0 mL of a solvent. The resulting solution has a vis\cosity of 1.25 cP. What is the molar mass of the polymer?

A. 5000 g/mol

B. 10000 g/mol

Correct C. 15000 g/mol

D. 20000 g/mol

Correct Answer: C

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Question 6

The reaction of cyclohexane with bromine in the presence of light produces 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 7

A sample of a polymer has a molecular weight of 100,000 g/mol. If the polymer is composed of 80% by weight of a monomer with a molecular weight of 50 g/mol, what is the number-average molecular weight of the polymer?

A. 50,000 g/mol

Correct B. 75,000 g/mol

C. 100,000 g/mol

D. 125,000 g/mol

Correct Answer: B

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Question 8

A 2.0 g sample of a non-metallic element is heated in a stream of oxygen gas. The resulting product is a white solid with a mass of 4.0 g. What is the empirical formula of the product?

A. O2

Correct B. SO2

C. SO3

D. S2O3

Correct Answer: B

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Question 9

A solution of a weak acid (HA) has a pH of 4.5. If 10 mL of this solution is added to 90 mL of a solution of a strong base (NaOH), what is the pH of the resulting solution?

A. 6.5

Correct B. 7.5

C. 8.5

D. 9.5

Correct Answer: B

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Question 10

A diagram of a titration setup is shown below. If 20 mL of a 0.1 M solution of NaOH is added to the burette, what is the volume of the acid solution required to reach the equivalence point?

A. 10 mL

B. 20 mL

Correct C. 30 mL

D. 40 mL

Correct Answer: C

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Question 11

Determine the pH of a 0.1 M solution of HCl. The dissociation cons\tant of HCl is 10^-7. Assuming complete dissociation, calculate the concentration of H+ ions.

Correct A. 1

B. 2

C. 3

D. 4

Correct Answer: A

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Question 12

A 2.5 L flask contains 0.5 mol of an ideal gas at 298 K. Calculate the work done by the gas when it expands to 5 L at cons\tant temperature.

A. 10 J

B. 20 J

Correct C. 30 J

D. 40 J

Correct Answer: C

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Question 13

A solution of 0.1 M HCl is titrated with 0.1 M NaOH. Calculate the pH of the solution after 20 mL of NaOH has been added.

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 14

A 10 g sample of a solid is dissolved in 100 mL of water. The resulting solution has a concentration of 0.1 M. Calculate the molar mass of the solid.

A. 100 g/mol

B. 200 g/mol

Correct C. 300 g/mol

D. 400 g/mol

Correct Answer: C

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Question 15

A 2.5 L flask contains 0.5 mol of an ideal gas at 298 K. Calculate the entropy change of the gas when it expands to 5 L at cons\tant temperature.

A. 10 J/K

B. 20 J/K

Correct C. 30 J/K

D. 40 J/K

Correct Answer: C

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Question 16

Determine the s\tandard enthalpy of formation of CH3OH(l) from the following data: ΔHf(CO2(g)) = -393.5 kJ/mol, ΔHf(H2O(l)) = -285.8 kJ/mol, ΔHf(CH4(g)) = -74.8 kJ/mol, ΔHf(O2(g)) = 0 kJ/mol.

Correct A. -238.7 kJ/mol

B. -285.8 kJ/mol

C. -393.5 kJ/mol

D. -74.8 kJ/mol

Correct Answer: A

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Question 17

A 2.50 M solution of HCl is titrated with 1.00 M NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the concentration of HCl?

A. 1.00 M

Correct B. 1.25 M

C. 2.00 M

D. 2.50 M

Correct Answer: B

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Question 18

The diagram below shows a titration setup. If 20.0 mL of NaOH is added to 30.0 mL of HCl, what is the pH of the resulting solution?

A. 1.00

Correct B. 2.00

C. 3.00

D. 4.00

Correct Answer: B

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Question 19

A 1.00 M solution of CH3OH is mixed with 2.00 M HCl. What is the resulting pH?

A. 1.00

B. 2.00

C. 3.00

Correct D. 4.00

Correct Answer: D

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Question 20

The diagram below shows a chemical apparatus setup. If 10.0 mL of HCl is added to 20.0 mL of NaOH, what is the resulting pH?

A. 1.00

Correct B. 2.00

C. 3.00

D. 4.00

Correct Answer: B

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Question 21

The reaction between chlorine gas and sodium iodide is represented by the equation: 2NaI(s) + Cl2(g) → 2NaCl(s) + I2(s). What is the oxidation state of iodine in the product I2(s)?

A. 0

B. -1

Correct C. 1

D. 2

Correct Answer: C

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Question 22

A 2.5 M solution of sulfuric acid (H2SO4) is prepared by dissolving 50 g of H2SO4 in water to make 250 mL of solution. What is the molarity of the solution?

A. 1.0 M

B. 2.0 M

Correct C. 2.5 M

D. 5.0 M

Correct Answer: C

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Question 23

The diagram below shows the structure of a molecule. What is the type of bond between atoms A and B?

Correct A. Sigma (σ) bond

B. Pi (π) bond

C. Sigma (σ) and Pi (π) bond

D. Hydrogen bond

Correct Answer: A

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Question 24

A 10% solution of sodium hydroxide (NaOH) is prepared by dissolving 10 g of NaOH in water to make 100 mL of solution. What is the molarity of the solution?

A. 0.1 M

B. 0.5 M

Correct C. 1.0 M

D. 2.0 M

Correct Answer: C

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Question 25

The reaction between sodium carbonate and hydrochloric acid is represented by the equation: Na2CO3(s) + 2HCl(aq) → 2NaCl(aq) + H2O(l) + CO2(g). What is the type of reaction?

A. Synthesis reaction

B. Decomposition reaction

Correct C. Neutralization reaction

D. Combustion reaction

Correct Answer: C

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