POST UTME KSU 2018 Chemistry | Objective

Are you preparing for POST UTME KSU exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2018 Chemistry (Objective) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1
Determine the number of moles of oxygen gas (O2) that will react with 2.5 moles of carbon monoxide (CO) in the following reaction: 2CO + O2 → 2CO2.
Correct A. 1.25 moles
B. 2.5 moles
C. 5 moles
D. 10 moles

Correct Answer: A

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Question 2
A sample of a polymer has a molecular weight of 50,000 g/mol. If 2.5 g of the polymer is dissolved in 100 mL of solvent, what is the concentration of the solution in g/L?
A. 0.05 g/L
Correct B. 0.5 g/L
C. 5 g/L
D. 50 g/L

Correct Answer: B

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Question 3
A solution of sodium chloride (NaCl) has a concentration of 0.1 M. If 10 mL of this solution is diluted to 100 mL with distilled water, what is the new concentration of the solution?
Correct A. 0.01 M
B. 0.1 M
C. 0.5 M
D. 1 M

Correct Answer: A

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Question 4
A sample of a non-metallic element has a mass of 2.5 g and a volume of 5 mL. If the density of the element is 2.5 g/mL, what is the percentage composition of the element?
Correct A. 50%
B. 60%
C. 70%
D. 80%

Correct Answer: A

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Question 5
A solution of sulfuric acid (H2SO4) has a concentration of 1 M. If 10 mL of this solution is added to 100 mL of distilled water, what is the new concentration of the solution?
A. 0.1 M
B. 0.5 M
Correct C. 1 M
D. 2 M

Correct Answer: C

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Question 6
Determine the s\tandard enthalpy change for the reaction: 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s). The s\tandard enthalpy of formation for Al2O3(s) is -1675 kJ/mol, and the s\tandard enthalpy of formation for Fe2O3(s) is -824 kJ/mol. The s\tandard enthalpy of formation for Al(s) is 0 kJ/mol, and the s\tandard enthalpy of formation for Fe(s) is 0 kJ/mol.
Correct A. -1874 kJ/mol
B. -1875 kJ/mol
C. -1876 kJ/mol
D. -1877 kJ/mol

Correct Answer: A

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Question 7
A 2.50 L flask contains 0.250 mol of an ideal gas at 298 K. Calculate the pressure of the gas u\sing the ideal gas law.
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 8
A solution contains 0.100 M NaCl. What is the concentration of Cl- ions in the solution?
A. 0.050 M
Correct B. 0.100 M
C. 0.150 M
D. 0.200 M

Correct Answer: B

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Question 9
A 0.500 L flask contains 0.250 mol of an ideal gas at 298 K. Calculate the number of moles of gas in a 1.00 L flask at 298 K.
A. 0.125 mol
Correct B. 0.250 mol
C. 0.375 mol
D. 0.500 mol

Correct Answer: B

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Question 10
A 2.00 L flask contains 0.500 mol of an ideal gas at 298 K. Calculate the pressure of the gas u\sing the ideal gas law.
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 11
Determine the number of unpaired electrons in the ground state of a neutral atom of the element with atomic number 13.
Correct A. 4
B. 6
C. 8
D. 10

Correct Answer: A

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Question 12
A 0.5 M solution of NaOH is mixed with a 0.2 M solution of HCl. What is the resulting pH after the reaction is complete?
A. 1
B. 2
C. 3
Correct D. 4

Correct Answer: D

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Question 13
A diagram of the atomic structure of an atom is shown below. What is the name of the region around the nucleus where electrons are most likely to be found?
A. Nucleus
Correct B. Electron Cloud
C. Protons
D. Neutrons

Correct Answer: B

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Question 14
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of CO(g)?
Correct A. -110.5 kJ/mol
B. -393.5 kJ/mol
C. -74.8 kJ/mol
D. -283.5 kJ/mol

Correct Answer: A

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Question 15
A diagram of a titration setup is shown below. What is the purpose of the burette?
Correct A. To measure the volume of the solution
B. To measure the pH of the solution
C. To measure the temperature of the solution
D. To measure the density of the solution

Correct Answer: A

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Question 16
Determine the number of moles of carbon dioxide produced when 2.5 g of calcium carbonate is decomposed completely at cons\tant pressure.
A. 0.05 mol
Correct B. 0.1 mol
C. 0.15 mol
D. 0.2 mol

Correct Answer: B

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Question 17
A 2.5 L flask contains 0.5 mol of an ideal gas at 300 K. Calculate the work done when the gas expands to 5 L at cons\tant temperature.
A. -150 J
B. -300 J
Correct C. -450 J
D. -600 J

Correct Answer: C

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Question 18
A sample of nitrogen gas occupies 2.5 L at 300 K. Calculate the pressure of the gas if the volume is reduced to 1.5 L at cons\tant temperature.
A. 1.5 atm
B. 2.0 atm
Correct C. 2.5 atm
D. 3.0 atm

Correct Answer: C

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Question 19
A 2.5 L flask contains 0.5 mol of an ideal gas at 300 K. Calculate the work done when the gas expands to 5 L at cons\tant temperature.
A. -150 J
B. -300 J
Correct C. -450 J
D. -600 J

Correct Answer: C

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Question 20
A sample of nitrogen gas occupies 2.5 L at 300 K. Calculate the pressure of the gas if the volume is reduced to 1.5 L at cons\tant temperature.
A. 1.5 atm
B. 2.0 atm
Correct C. 2.5 atm
D. 3.0 atm

Correct Answer: C

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Question 21
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CaCO3(s) u\sing the following reaction: CaO(s) + CO2(g) → CaCO3(s).
Correct A. -1781.8 kJ/mol
B. -1781.9 kJ/mol
C. -1782.0 kJ/mol
D. -1782.1 kJ/mol

Correct Answer: A

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Question 22
A 2.50 M solution of HCl is mixed with a 1.00 M solution of NaOH. Calculate the pH of the resulting solution.
A. 2.00
Correct B. 2.50
C. 3.00
D. 3.50

Correct Answer: B

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Question 23
The half-life of a radioactive subs\tance is 5.00 years. If 100.0 g of the subs\tance initially exists, how much will remain after 20.0 years?
Correct A. 12.5 g
B. 25.0 g
C. 37.5 g
D. 50.0 g

Correct Answer: A

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Question 24
A 1.00 M solution of H2SO4 is mixed with a 2.00 M solution of NaOH. Calculate the pH of the resulting solution.
A. 1.00
B. 2.00
C. 3.00
Correct D. 4.00

Correct Answer: D

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Question 25
A 2.00 M solution of NH3 is mixed with a 1.00 M solution of HCl. Calculate the pH of the resulting solution.
A. 1.00
B. 2.00
Correct C. 3.00
D. 4.00

Correct Answer: C

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