POST UTME KSU 2023 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 2023 Chemistry (Objective) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1
Determine the pH of a 0.1 M solution of hydrochloric acid (HCl) at 25°C.
A. 1
B. 2
C. 3
Correct D. 4

Correct Answer: D

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Question 2
A 25 mL sample of a solution containing 0.5 M NaOH is titrated with 0.5 M HCl. Calculate the volume of HCl required to reach the equivalence point.
A. 12.5 mL
B. 25 mL
Correct C. 37.5 mL
D. 50 mL

Correct Answer: C

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Question 3
A sample of a polymer is analyzed by gel permeation chromatography (GPC). The chromatogram shows a peak at 10 minutes with a retention time of 20 minutes. What is the molecular weight of the polymer?
A. 10^4 g/mol
B. 10^5 g/mol
Correct C. 10^6 g/mol
D. 10^7 g/mol

Correct Answer: C

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Question 4
A 2.0 g sample of a non-metallic oxide is analyzed by acid-base titration. The titration curve shows a pH of 7 at the equivalence point. What is the molar mass of the oxide?
A. 50 g/mol
Correct B. 100 g/mol
C. 150 g/mol
D. 200 g/mol

Correct Answer: B

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Question 5
A diagram of a titration setup is shown below.
A. The burette contains NaOH.
B. The beaker contains HCl.
C. The burette contains HCl.
Correct D. The beaker contains NaOH.

Correct Answer: D

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Question 6
A sample of a metal oxide, M2O3, has a mass of 25.0 g and a volume of 2.50 cm3. If the density of the metal oxide is 5.50 g/cm3, calculate the molar mass of M2O3.
A. 0.250 kg/mol
B. 0.500 kg/mol
Correct C. 1.00 kg/mol
D. 2.00 kg/mol

Correct Answer: C

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Question 7
A 2.50 M solution of HCl is titrated with a 1.00 M solution of NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, calculate the number of moles of HCl present in 100.0 mL of the HCl solution.
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 8
A sample of a gas has a volume of 2.50 L at a pressure of 1.00 atm and a temperature of 25.0°C. If the pressure is increased to 2.00 atm and the temperature is increased to 50.0°C, calculate the new volume of the gas.
A. 3.13 L
B. 4.00 L
Correct C. 5.00 L
D. 6.25 L

Correct Answer: C

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Question 9
A 2.00 M solution of NaOH is titrated with a 1.00 M solution of HCl. If 25.0 mL of HCl is required to reach the equivalence point, calculate the pH of the resulting solution.
A. 0.000
B. 1.000
Correct C. 2.000
D. 3.000

Correct Answer: C

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Question 10
A sample of a metal, M, has a mass of 25.0 g and a volume of 2.50 cm3. If the density of the metal is 5.50 g/cm3, calculate the molar mass of M.
A. 0.250 kg/mol
B. 0.500 kg/mol
Correct C. 1.00 kg/mol
D. 2.00 kg/mol

Correct Answer: C

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Question 11
A 2.0 g sample of an unknown hydrocarbon is burned in a combustion calorimeter, producing 3.2 g of CO2 and 1.8 g of H2O. Calculate the empirical formula of the hydrocarbon.
Correct A. C2H4
B. C3H6
C. C4H8
D. C5H10

Correct Answer: A

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Question 12
A metal (X) reacts with chlorine gas to form a white solid. The reaction is as follows: 2X + Cl2 → 2XCl. If 2.5 g of X reacts with 1.8 g of Cl2, calculate the molar mass of X.
A. 50 g/mol
Correct B. 75 g/mol
C. 100 g/mol
D. 125 g/mol

Correct Answer: B

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Question 13
A solution of NaCl is electrolyzed u\sing a platinum electrode. The anode reaction is 2Cl- → Cl2 + 2e-. If 2.5 A of current is passed through the solution for 10 minutes, calculate the mass of Cl2 produced.
A. 0.25 g
Correct B. 0.5 g
C. 1.0 g
D. 1.5 g

Correct Answer: B

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Question 14
A sample of a metal (X) has a density of 8.5 g/cm3 and a volume of 2.5 cm3. If the metal is 85% pure, calculate the mass of the impurities present.
A. 0.25 g
Correct B. 0.5 g
C. 1.0 g
D. 1.5 g

Correct Answer: B

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Question 15
A solution of H2SO4 is 80% by mass. If 250 mL of the solution has a mass of 220 g, calculate the molarity of the solution.
A. 1.0 M
Correct B. 2.0 M
C. 3.0 M
D. 4.0 M

Correct Answer: B

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Question 16
A metal alloy is composed of 75% copper and 25% zinc. If 500g of the alloy is heated to 1000°C, what is the mass of copper that will be oxidized?
A. 125g
B. 150g
Correct C. 175g
D. 200g

Correct Answer: C

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Question 17
A solution of 0.1M NaOH is mixed with a solution of 0.1M HCl. What is the pH of the resulting solution?
A. 7
Correct B. 8
C. 9
D. 10

Correct Answer: B

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Question 18
A sample of water contains 10ppm of dissolved oxygen. What is the concentration of oxygen in mg/L?
Correct A. 10mg/L
B. 20mg/L
C. 30mg/L
D. 40mg/L

Correct Answer: A

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Question 19
A solution of 0.1M NaOH is mixed with a solution of 0.1M HCl. What is the concentration of the resulting solution?
A. 0.05M
Correct B. 0.1M
C. 0.15M
D. 0.2M

Correct Answer: B

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Question 20
A metal alloy is composed of 75% copper and 25% zinc. If 500g of the alloy is heated to 1000°C, what is the mass of zinc that will be oxidized?
A. 125g
Correct B. 150g
C. 175g
D. 200g

Correct Answer: B

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