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POST UTME CALEB UNIVERSITY 2021 Chemistry | Objective

Are you preparing for POST UTME CALEB UNIVERSITY exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2021 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) produced at 298 K and 1 atm when 2.50 g of potassium chlorate (KClO3) decomposes according to the equation: 2KClO3(s) → 2KCl(s) + 3O2(g).

Correct A. 0.0500 mol

B. 0.100 mol

C. 0.150 mol

D. 0.200 mol

Correct Answer: A

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Question 2

A 2.0 M solution of HCl is titrated with a 1.0 M solution of NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the volume of HCl used?

A. 12.5 mL

Correct B. 25.0 mL

C. 37.5 mL

D. 50.0 mL

Correct Answer: B

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Question 3

A sample of a gas occupies 2.50 L at 25°C and 1.00 atm. What is the pressure of the gas at 50°C and 3.00 atm?

A. 1.50 atm

B. 2.00 atm

Correct C. 2.50 atm

D. 3.00 atm

Correct Answer: C

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Question 4

A 0.100 M solution of H2SO4 is titrated with a 0.100 M solution of NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the pH of the solution?

A. 1.00

B. 2.00

C. 3.00

Correct D. 4.00

Correct Answer: D

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Question 5

A 2.0 M solution of HCl is titrated with a 1.0 M solution of NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the volume of HCl used?

A. 12.5 mL

Correct B. 25.0 mL

C. 37.5 mL

D. 50.0 mL

Correct Answer: B

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Question 6

Determine the rate cons\tant (k) for the reaction: 2NO(g) + O2(g) → 2NO2(g), given that the initial concentrations of NO and O2 are 0.1 M and 0.2 M, respectively, and the rate cons\tant is 0.05 M^$ -1 $s^$ -1 $ at 298 K. The reaction is first-order with respect to NO and zero-order with respect to O2.

Correct A. 0.05 M^$ -1 $s^$ -1 $

B. 0.1 M^$ -1 $s^$ -1 $

C. 0.2 M^$ -1 $s^$ -1 $

D. 0.3 M^$ -1 $s^$ -1 $

Correct Answer: A

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Question 7

A polymer is formed from the reaction of 1,4-butadiene with sulfur dichloride (SCl2). The polymer has a molecular weight of 50,000 g/mol and a degree of polymerization of 200. What is the molar mass of the repeating unit?

A. 250 g/mol

Correct B. 500 g/mol

C. 750 g/mol

D. 1000 g/mol

Correct Answer: B

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Question 8

A solution of 0.1 M HCl is titrated with 0.1 M NaOH. If 20 mL of NaOH is added, what is the pH of the solution?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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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 partial pressure of water vapor is 0.02 atm, what is the mole \fraction of nitrogen gas?

A. 0.98

B. 0.99

Correct C. 0.995

D. 0.999

Correct Answer: C

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Question 10

A solution of 0.1 M HCl is titrated with 0.1 M NaOH. If 20 mL of NaOH is added, what is the concentration of HCl remaining in the solution?

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 11

A 0.1 M solution of a weak electrolyte is prepared by dissolving 0.1 g of the electrolyte in 100 mL of water. Calculate the number of moles of the electrolyte dissolved.

Correct A. 0.001 mol

B. 0.01 mol

C. 0.1 mol

D. 1 mol

Correct Answer: A

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Question 12

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CH4(g) from the following equation: CH4(g) + 2O2(g) → CO2(g) + 2H2O(l).

A. -74.8 kJ/mol

B. -74.9 kJ/mol

Correct C. -75.0 kJ/mol

D. -75.1 kJ/mol

Correct Answer: C

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Question 13

A 2.0 M solution of a strong acid is prepared by dissolving 2.0 g of the acid in 100 mL of water. Calculate the pH of the solution.

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 14

The s\tandard enthalpy of formation of H2O(l) is -285.8 kJ/mol. Calculate the s\tandard enthalpy of formation of H2(g) from the following equation: H2(g) + 1/2O2(g) → H2O(l).

Correct A. 0 kJ/mol

B. -0.1 kJ/mol

C. -0.2 kJ/mol

D. -0.3 kJ/mol

Correct Answer: A

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Question 15

A 1.0 M solution of a weak base is prepared by dissolving 1.0 g of the base in 100 mL of water. Calculate the pOH of the solution.

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 16

A 0.1 M solution of NaCl is prepared by dissolving 2.5 g of NaCl in 100 mL of water. Calculate the molarity of the solution after 10 mL of 1 M HCl is added to it.

A. 0.15 M

Correct B. 0.20 M

C. 0.25 M

D. 0.30 M

Correct Answer: B

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Question 17

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CH4(g) if the s\tandard enthalpy of formation of C(s) is -394.4 kJ/mol and that of H2(g) is 0 kJ/mol.

A. -74.8 kJ/mol

B. -74.9 kJ/mol

Correct C. -75.0 kJ/mol

D. -75.1 kJ/mol

Correct Answer: C

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Question 18

A 2.5 L flask contains 0.5 mol of CO2 at 298 K. Calculate the partial pressure of CO2 in the flask.

Correct A. 1.01 atm

B. 1.02 atm

C. 1.03 atm

D. 1.04 atm

Correct Answer: A

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Question 19

A 0.1 M solution of NaOH is prepared by dissolving 2.5 g of NaOH in 100 mL of water. Calculate the pH of the solution after 10 mL of 1 M HCl is added to it.

A. 1.0

Correct B. 2.0

C. 3.0

D. 4.0

Correct Answer: B

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Question 20

A 2.5 L flask contains 0.5 mol of CO2 at 298 K. Calculate the mole \fraction of CO2 in the flask.

Correct A. 0.2

B. 0.3

C. 0.4

D. 0.5

Correct Answer: A

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Question 21

Determine the number of moles of $\text{CO}_2$ produced when 2.50 g of $\text{CaC}_2$ is completely decomposed at 25°C and 1 atm.

A. 0.0250 mol

Correct B. 0.0500 mol

C. 0.100 mol

D. 0.200 mol

Correct Answer: B

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Question 22

A 0.500 M solution of $\text{H}_2\text{SO}_4$ is mixed with 0.500 M solution of $\text{Ba(OH)}_2$. If the reaction is complete, what is the concentration of the resulting solution?

A. 0.250 M

B. 0.500 M

Correct C. 0.750 M

D. 1.00 M

Correct Answer: C

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Question 23

A sample of $\text{CO}_2$ gas occupies a volume of 2.50 L at a pressure of 0.800 atm. What is the volume of the gas at a pressure of 1.20 atm, assuming the temperature remains cons\tant?

A. 1.50 L

Correct B. 2.00 L

C. 2.50 L

D. 3.00 L

Correct Answer: B

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Question 24

A 2.00 M solution of $\text{NaOH}$ is mixed with 2.00 M solution of $\text{HCl}$. If the reaction is complete, what is the concentration of the resulting solution?

A. 0.500 M

Correct B. 1.00 M

C. 1.50 M

D. 2.00 M

Correct Answer: B

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Question 25

A sample of $\text{H}_2$ gas occupies a volume of 3.00 L at a pressure of 0.500 atm. What is the volume of the gas at a pressure of 1.00 atm, assuming the temperature remains cons\tant?

A. 1.50 L

B. 2.00 L

Correct C. 3.00 L

D. 4.00 L

Correct Answer: C

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