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POST UTME NOUN 2023 Chemistry | Objective

Are you preparing for POST UTME NOUN exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2023 Chemistry (Objective) questions designed to simulate the real exam environment.

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Question 1

The reaction between sulfuric acid and sodium hydroxide is a classic example of a double displacement reaction. What is the chemical equation for this reaction?

Correct A. \text{H}_2\text{SO}_4 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O}

B. \text{H}_2\text{SO}_4 + \text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + \text{H}_2\text{O}

C. \text{H}_2\text{SO}_4 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + \text{H}_2\text{O}

D. \text{H}_2\text{SO}_4 + \text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O}

Correct Answer: A

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Question 2

A solution of sodium chloride is prepared by dissolving 35.5 g of sodium chloride in 100 mL of water. 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 3

A diagram of a titration setup is shown below. What is the purpose of the burette in this setup?

Correct A. To measure the volume of the solution

B. To measure the concentration of the solution

C. To mix the solution with the analyte

D. To separate the solution from the analyte

Correct Answer: A

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Question 4

A solution of sulfuric acid is prepared by dissolving 25 g of sulfuric acid in 100 mL of water. What is the concentration of the solution in terms of molarity?

A. 0.5 M

Correct B. 1.0 M

C. 2.0 M

D. 5.0 M

Correct Answer: B

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Question 5

A diagram of a chromatography setup is shown below. What is the purpose of the stationary phase in this setup?

Correct A. To separate the components of the mixture

B. To identify the components of the mixture

C. To measure the concentration of the mixture

D. To separate the solvent from the solute

Correct Answer: A

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Question 6

The rate cons\tant (k) of 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^\( -1 \)?

Correct A. 1.0 x 10^\( -10 \) s^\( -1 \)

B. 1.0 x 10^\( -9 \) s^\( -1 \)

C. 1.0 x 10^\( -8 \) s^\( -1 \)

D. 1.0 x 10^\( -7 \) s^\( -1 \)

Correct Answer: A

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Question 7

A solution of 0.1 M NaOH is titrated with 0.1 M HCl. What is the pH of the solution after 25 mL of HCl has been added to 25 mL of NaOH?

A. 1.0

Correct B. 2.0

C. 3.0

D. 4.0

Correct Answer: B

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Question 8

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. 200 g/mol

B. 400 g/mol

Correct C. 600 g/mol

D. 800 g/mol

Correct Answer: C

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Question 9

A sample of nitrogen gas is collected over water at a temperature of 25°C and a pressure of 1 atm. If the vapor pressure of water at 25°C is 23.8 mmHg, what is the partial pressure of nitrogen gas?

A. 760 mmHg

Correct B. 737 mmHg

C. 714 mmHg

D. 691 mmHg

Correct Answer: B

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Question 10

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

A. 1.0

B. 2.0

C. 3.0

Correct D. 4.0

Correct Answer: D

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Question 11

A 0.1 M solution of a strong acid is titrated with 0.1 M NaOH. If 25 mL of the acid is required to reach the equivalence point, what is the volume of NaOH required to reach the equivalence point in a 0.05 M solution of the acid?

A. 50 mL

B. 25 mL

Correct C. 12.5 mL

D. 100 mL

Correct Answer: C

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Question 12

A sample of a polymer is analyzed by gel permeation chromatography (GPC). The chromatogram shows a \single peak with a retention time of 10 minutes. What is the molecular weight of the polymer?

A. 1000 g/mol

B. 10000 g/mol

Correct C. 100000 g/mol

D. 1000000 g/mol

Correct Answer: C

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Question 13

A 2 M solution of a weak acid is titrated with 2 M NaOH. If 10 mL of the acid is required to reach the equivalence point, what is the pH of the solution at the equivalence point?

Correct A. 7

B. 9

C. 11

D. 13

Correct Answer: A

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Question 14

A 1 M solution of a salt is analyzed by ion chromatography (IC). The chromatogram shows two peaks with retention times of 5 minutes and 10 minutes. What is the molar ratio of the two ions?

Correct A. 1:1

B. 2:1

C. 1:2

D. 3:1

Correct Answer: A

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Question 15

A sample of a polymer is analyzed by size exclusion chromatography (SEC). The chromatogram shows a \single peak with a retention time of 15 minutes. What is the molecular weight 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 16

Determine the number of moles of oxygen gas (O2) required to completely combust 2.50 moles of propane (C3H8) according to the balanced equation: C3H8 + 5O2 → 3CO2 + 4H2O.

A. 1.25 moles

Correct B. 2.50 moles

C. 3.75 moles

D. 5.00 moles

Correct Answer: B

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Question 17

A sample of a non-metallic element has a mass of 25.0 g and a density of 3.50 g/cm3. What is the volume of the sample in cubic centimeters?

A. 5.71 cm3

Correct B. 7.14 cm3

C. 10.0 cm3

D. 14.3 cm3

Correct Answer: B

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Question 18

A solution contains 2.50 g of sodium chloride (NaCl) dissolved in 100.0 mL of water. What is the molarity of the 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 19

A gas at s\tandard temperature and pressure (STP) has a volume of 22.4 L. What is the number of moles of the gas?

Correct A. 1.00 mol

B. 2.00 mol

C. 3.00 mol

D. 4.00 mol

Correct Answer: A

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Question 20

A solution contains 10.0 g of glu\cose (C6H12O6) dissolved in 100.0 mL of water. What is the concentration of the solution in grams per liter?

A. 10.0 g/L

B. 20.0 g/L

Correct C. 30.0 g/L

D. 40.0 g/L

Correct Answer: C

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