POST UTME OAU 2020 Chemistry | Objective

Are you preparing for POST UTME OAU exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2020 Chemistry (Objective) questions designed to simulate the real exam environment.

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Question 1
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution after 25.0 mL of NaOH has been added.
A. \( pH = 7 \)
B. \( pH = 3 \)
Correct C. \( pH = 10 \)
D. \( pH = 12 \)

Correct Answer: C

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Question 2
A solution contains 0.500 mol of NaCl. If 0.250 mol of CaCl2 is added to the solution, what is the total number of moles of ions present in the solution?
A. 1.75
B. 2.25
Correct C. 2.50
D. 3.00

Correct Answer: C

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Question 3
A diagram of a titration setup is shown below. If 25.0 mL of 0.100 M HCl is titrated with 0.100 M NaOH, what is the pH of the solution after 25.0 mL of NaOH has been added?
A. \( pH = 7 \)
B. \( pH = 3 \)
Correct C. \( pH = 10 \)
D. \( pH = 12 \)

Correct Answer: C

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Question 4
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. If 25.0 mL of NaOH has been added, what is the concentration of the acid in the solution?
A. 0.050 M
Correct B. 0.100 M
C. 0.200 M
D. 0.500 M

Correct Answer: B

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Question 5
A diagram of a titration setup is shown below. If 25.0 mL of 0.100 M HCl is titrated with 0.100 M NaOH, what is the pH of the solution after 25.0 mL of NaOH has been added?
A. \( pH = 7 \)
B. \( pH = 3 \)
Correct C. \( pH = 10 \)
D. \( pH = 12 \)

Correct Answer: C

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Question 6
Determine the major product of the reaction between 2-methylpropene and HBr.
Correct A. 1-bromo-2-methylpropane
B. 2-bromo-2-methylpropane
C. 1-bromo-3-methylbu\tane
D. 2-bromo-3-methylbu\tane

Correct Answer: A

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Question 7
Calculate the equilibrium cons\tant (Kc) for the reaction: N2(g) + 3H2(g) ⇌ 2NH3(g), given that Kp = 0.050 at 500°C.
Correct A. 0.050
B. 0.050^3
C. 2*0.050
D. 0.050^2

Correct Answer: A

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Question 8
A 2.50 L flask contains 0.250 mol of CO2 at 25°C. Calculate the partial pressure of CO2 in the flask.
Correct A. 0.100 atm
B. 0.250 atm
C. 0.500 atm
D. 1.00 atm

Correct Answer: A

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Question 9
A 50.0 mL sample of a 0.100 M solution of NaOH is mixed with 50.0 mL of a 0.100 M solution 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 10
A 25.0 g sample of a mixture of NaCl and KCl is dissolved in water and the resulting solution is electrolyzed. If 12.5 g of Cl2 is collected at the anode, what is the mass of KCl in the original mixture?
A. 10.0 g
Correct B. 12.5 g
C. 15.0 g
D. 20.0 g

Correct Answer: B

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Question 11
Determine the number of moles of electrons transferred in the electrolysis of 1.5 L of 0.25 M H2SO4. The reaction is: 2H+ + 2e- → H2.
A. 0.375 mol
Correct B. 0.75 mol
C. 1.5 mol
D. 3 mol

Correct Answer: B

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Question 12
A polymer is formed by the condensation reaction of 1 mole of ethylene glycol with 1 mole of terephthalic acid. If the molecular weight of the polymer is 200 g/mol, what is the degree of polymerization?
A. 2
B. 4
Correct C. 6
D. 8

Correct Answer: C

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Question 13
A solution of 0.1 M NaOH is mixed with a solution of 0.1 M HCl. What is the pH of the resulting solution?
Correct A. 7
B. 8
C. 9
D. 10

Correct Answer: A

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Question 14
A sample of 1.5 L of 0.25 M H2SO4 is electrolyzed. If the current is 2 A, what is the mass of hydrogen gas collected at the cathode?
A. 0.5 g
B. 1 g
Correct C. 2 g
D. 4 g

Correct Answer: C

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Question 15
A polymer is formed by the condensation reaction of 1 mole of ethylene glycol with 1 mole of terephthalic acid. If the molecular weight of the polymer is 200 g/mol, what is the molar mass of the repeating unit?
A. 100 g/mol
B. 150 g/mol
Correct C. 200 g/mol
D. 250 g/mol

Correct Answer: C

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Question 16
A 2.5 M solution of NaOH is prepared by dissolving 12.5 g of NaOH in 500 mL of water. Calculate the concentration of the solution in mol/L.
Correct A. 2.5 M
B. 1.25 M
C. 5 M
D. 10 M

Correct Answer: A

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Question 17
A 1.0 M solution of HCl is prepared by dissolving 36.5 g of HCl in 1 L of water. Calculate the concentration of the solution in mol/L.
Correct A. 1.0 M
B. 0.5 M
C. 2.0 M
D. 3.0 M

Correct Answer: A

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Question 18
A 2.0 M solution of NaOH is prepared by dissolving 40 g of NaOH in 1 L of water. Calculate the concentration of the solution in mol/L.
Correct A. 2.0 M
B. 1.0 M
C. 3.0 M
D. 4.0 M

Correct Answer: A

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Question 19
A 1.5 M solution of HCl is prepared by dissolving 45 g of HCl in 1 L of water. Calculate the concentration of the solution in mol/L.
Correct A. 1.5 M
B. 0.5 M
C. 2.5 M
D. 3.5 M

Correct Answer: A

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Question 20
A 3.0 M solution of NaOH is prepared by dissolving 60 g of NaOH in 1 L of water. Calculate the concentration of the solution in mol/L.
Correct A. 3.0 M
B. 1.5 M
C. 4.5 M
D. 5.5 M

Correct Answer: A

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Question 21
A solution containing 0.5 M NaCl is electrolyzed u\sing a platinum electrode. If the electrolysis is carried out for 2 hours, and the current is 0.5 A, calculate the mass of chlorine gas evolved at the anode.
A. 0.5 g
B. 1.0 g
Correct C. 2.0 g
D. 3.0 g

Correct Answer: C

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Question 22
A 2.0 M solution of HCl is titrated with 0.5 M NaOH. If 25 mL of NaOH is required to reach the equivalence point, calculate the volume of HCl required to reach the equivalence point.
A. 50 mL
B. 75 mL
Correct C. 100 mL
D. 125 mL

Correct Answer: C

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Question 23
A sample of gas has a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 25°C. If the pressure is increased to 3.0 atm and the temperature is increased to 50°C, calculate the new volume of the gas.
A. 3.0 L
B. 4.0 L
Correct C. 5.0 L
D. 6.0 L

Correct Answer: C

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Question 24
A 1.0 M solution of FeSO4 is electrolyzed u\sing a platinum electrode. If the electrolysis is carried out for 1 hour, and the current is 0.2 A, calculate the mass of iron deposited at the cathode.
A. 0.5 g
Correct B. 1.0 g
C. 2.0 g
D. 3.0 g

Correct Answer: B

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Question 25
A 2.0 M solution of H2SO4 is titrated with 0.5 M NaOH. If 30 mL of NaOH is required to reach the equivalence point, calculate the volume of H2SO4 required to reach the equivalence point.
A. 60 mL
B. 75 mL
Correct C. 100 mL
D. 125 mL

Correct Answer: C

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