POST UTME UI 2022 Chemistry | Objective

Are you preparing for POST UTME UI exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2022 Chemistry (Objective) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1
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(C(s)) = 0 kJ/mol.
Correct A. -1206.60 kJ/mol
B. -1206.10 kJ/mol
C. -1207.10 kJ/mol
D. -1207.60 kJ/mol

Correct Answer: A

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Question 2
The s\tandard Gibbs free energy of formation of Fe2O3(s) is -742.2 kJ/mol. Calculate the s\tandard Gibbs free energy of formation of FeO(s) if the s\tandard Gibbs free energy of formation of Fe(s) is 0 kJ/mol.
A. -742.2 kJ/mol
Correct B. -742.5 kJ/mol
C. -742.8 kJ/mol
D. -743.0 kJ/mol

Correct Answer: B

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Question 3
A 2.50-g sample of a non-metallic element, X, reacts with oxygen to form 3.25 g of X2O3. Calculate the empirical formula of X.
Correct A. X2O3
B. XO2
C. X2O5
D. XO3

Correct Answer: A

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Question 4
The atomic radius of a certain metal, M, is 0.125 nm. If the atomic radius of M is 0.125 nm, what is the atomic radius of M2+?
Correct A. 0.0625 nm
B. 0.125 nm
C. 0.1875 nm
D. 0.250 nm

Correct Answer: A

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Question 5
A 2.50-g sample of a non-metallic element, X, reacts with oxygen to form 3.25 g of X2O3. Calculate the molar mass of X.
A. 40.0 g/mol
Correct B. 50.0 g/mol
C. 60.0 g/mol
D. 70.0 g/mol

Correct Answer: B

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Question 6
Determine the number of moles of ΔH₂O(g) produced when 2.50 g of H₂(g) reacts with O₂(g) according to the equation: 2H₂(g) + O₂(g) → 2ΔH₂O(g).
A. 0.0500 mol
Correct B. 0.100 mol
C. 0.200 mol
D. 0.500 mol

Correct Answer: B

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Question 7
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?
Correct A. 1.43 cm³
B. 2.14 cm³
C. 3.50 cm³
D. 5.00 cm³

Correct Answer: A

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Question 8
A solution contains 0.100 M H₂SO₄(aq) and 0.0500 M NaOH(aq). What is the pH of the solution after the reaction is complete?
A. 1.00
Correct B. 2.00
C. 3.00
D. 4.00

Correct Answer: B

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Question 9
A 0.500 L sample of a gas at 25.0°C and 1.00 atm is collected over water. What is the partial pressure of the gas?
A. 0.900 atm
B. 0.950 atm
Correct C. 1.00 atm
D. 1.05 atm

Correct Answer: C

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Question 10
A 0.100 M solution of Na₂CO₃(aq) is mixed with a 0.100 M solution of Ca(OH)₂(aq). What is the molarity of the resulting solution?
A. 0.0500 M
B. 0.100 M
Correct C. 0.150 M
D. 0.200 M

Correct Answer: C

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Question 11
The reaction of zinc metal with copper(II) sulfate solution is a classic example of a redox reaction. Write the balanced chemical equation for this reaction, including the states of matter for all reac\tants and products.
Correct A. Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)
B. Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu2+(aq)
C. Zn(s) + CuSO4(aq) → Zn2+(aq) + Cu(s)
D. Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu2+(aq)

Correct Answer: A

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Question 12
The enthalpy change (ΔH) for the combustion of methane (CH4) is -890 kJ/mol. If 2.5 mol of methane is burned, what is the total enthalpy change for this reaction?
Correct A. -2225 kJ
B. -2220 kJ
C. -2215 kJ
D. -2210 kJ

Correct Answer: A

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Question 13
The molecular formula for a hydrocarbon is C5H12. What is the name of this compound?
Correct A. Pen\tane
B. Hexane
C. Hep\tane
D. Oc\tane

Correct Answer: A

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Question 14
The entropy change (ΔS) for the vaporization of water is 109 J/mol·K. If 10 g of water is vaporized, what is the total entropy change for this process?
Correct A. 1090 J/K
B. 1080 J/K
C. 1070 J/K
D. 1060 J/K

Correct Answer: A

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Question 15
The diagram below shows a simple electrolysis setup. What is the purpose of the anode in this setup?
A. To conduct electricity
Correct B. To produce hydrogen gas
C. To produce oxygen gas
D. To act as a catalyst

Correct Answer: B

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Question 16
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. The s\tandard enthalpy of formation of H2O(l) is -285.8 kJ/mol. Calculate the s\tandard enthalpy of formation of CH4(g) u\sing Hess's Law.
Correct A. -74.8 kJ/mol
B. -74.2 kJ/mol
C. -75.6 kJ/mol
D. -76.1 kJ/mol

Correct Answer: A

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Question 17
A 2.50 L flask contains 0.150 mol of CO2 at 25°C. What is the partial pressure of CO2 in the flask?
A. 0.120 atm
Correct B. 0.150 atm
C. 0.180 atm
D. 0.200 atm

Correct Answer: B

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Question 18
A 0.500 M solution of HCl is titrated with 0.500 M NaOH. What is the pH of the solution after 25.0 mL of NaOH has been added?
A. 1.00
B. 2.00
Correct C. 3.00
D. 4.00

Correct Answer: C

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Question 19
A 1.00 L flask contains 0.100 mol of NaCl. What is the concentration of Na+ ions in the solution?
Correct A. 0.100 M
B. 0.200 M
C. 0.300 M
D. 0.400 M

Correct Answer: A

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Question 20
A 2.00 L flask contains 0.500 mol of CO2. What is the mole \fraction of CO2 in the flask?
A. 0.250
B. 0.333
Correct C. 0.500
D. 0.667

Correct Answer: C

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Question 21
A 1.00 L flask contains 0.100 mol of H2O. What is the concentration of H2O in the solution?
Correct A. 0.100 M
B. 0.200 M
C. 0.300 M
D. 0.400 M

Correct Answer: A

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Question 22
A 2.00 L flask contains 0.500 mol of CO2. What is the partial pressure of CO2 in the flask?
A. 0.120 atm
Correct B. 0.150 atm
C. 0.180 atm
D. 0.200 atm

Correct Answer: B

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Question 23
A 1.00 L flask contains 0.100 mol of NaCl. What is the concentration of Na+ ions in the solution?
Correct A. 0.100 M
B. 0.200 M
C. 0.300 M
D. 0.400 M

Correct Answer: A

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Question 24
A 2.00 L flask contains 0.500 mol of CO2. What is the mole \fraction of CO2 in the flask?
A. 0.250
B. 0.333
Correct C. 0.500
D. 0.667

Correct Answer: C

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Question 25
A solution of $NH_4Cl$ in water is prepared by dissolving $10.0,g$ of $NH_4Cl$ in $100,mL$ of water. If the density of the solution is $1.05,g/mL$, calculate the molarity of the solution.
A. 0.5 M
Correct B. 1.0 M
C. 1.5 M
D. 2.0 M

Correct Answer: B

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