POST UTME CALEB UNIVERSITY 2024 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 2024 Chemistry (Objective) questions designed to simulate the real exam environment.

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Question 1
A 0.5 M solution of a weak acid HA is mixed with a 0.5 M solution of a strong base NaOH in a 1:1 mole ratio. If the initial temperature of the solution is 25°C, and the reaction is carried out in a calorimeter, what is the expected change in the entropy of the system?
A. An increase in entropy due to the formation of a new compound
Correct B. A decrease in entropy due to the formation of a new compound
C. No change in entropy \since the reaction is at equilibrium
D. An increase in entropy due to the release of heat

Correct Answer: B

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Question 2
A polymer chain has a molecular weight of 100,000 g/mol and a degree of polymerization of 500. What is the molar mass of the repeating unit?
A. 100 g/mol
B. 200 g/mol
Correct C. 500 g/mol
D. 1000 g/mol

Correct Answer: C

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Question 3
A 1.0 M solution of ethanol (C2H5OH) is mixed with a 1.0 M solution of water (H2O) in a 1:1 mole ratio. What is the expected pH of the resulting solution?
A. 0
B. 1
C. 2
Correct D. 7

Correct Answer: D

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Question 4
A gas is confined to a container with a volume of 2.0 L at a temperature of 300 K. If the temperature is increased to 400 K, what is the expected change in the pressure of the gas?
Correct A. An increase in pressure
B. A decrease in pressure
C. No change in pressure
D. A decrease in volume

Correct Answer: A

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Question 5
A metal alloy is composed of 80% copper and 20% zinc. If the density of the alloy is 8.5 g/cm^3, what is the expected density of the copper component?
A. 8.5 g/cm^3
Correct B. 9.0 g/cm^3
C. 9.5 g/cm^3
D. 10.0 g/cm^3

Correct Answer: B

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Question 6
A mixture of 2.5 g of an unknown hydrocarbon and 2.5 g of anhydrous CaCl2 was dissolved in 25 mL of diethyl ether. The solution was then titrated with 0.1 M AgNO3. The reaction was monitored u\sing a burette, and the volume of AgNO3 required to reach the equivalence point was 15 mL. Calculate the molar mass of the hydrocarbon.
A. 50 g/mol
B. 75 g/mol
Correct C. 100 g/mol
D. 125 g/mol

Correct Answer: C

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Question 7
A sample of a polymer was dissolved in 100 mL of chloroform. The solution was then titrated with 0.1 M HCl until a pH of 3 was reached. If 20 mL of HCl was required to reach the equivalence point, calculate the number of moles of HCl used.
A. 0.002 mol
Correct B. 0.004 mol
C. 0.006 mol
D. 0.008 mol

Correct Answer: B

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Question 8
A solution of 0.1 M HCl was titrated with 0.1 M NaOH until a pH of 7 was reached. If 20 mL of NaOH was required to reach the equivalence point, calculate the number of moles of HCl used.
A. 0.002 mol
Correct B. 0.004 mol
C. 0.006 mol
D. 0.008 mol

Correct Answer: B

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Question 9
A mixture of 2.5 g of an unknown hydrocarbon and 2.5 g of anhydrous CaCl2 was dissolved in 25 mL of diethyl ether. The solution was then titrated with 0.1 M AgNO3. The reaction was monitored u\sing a burette, and the volume of AgNO3 required to reach the equivalence point was 15 mL. Calculate the molar mass of the hydrocarbon.
A. 50 g/mol
B. 75 g/mol
Correct C. 100 g/mol
D. 125 g/mol

Correct Answer: C

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Question 10
A sample of a polymer was dissolved in 100 mL of chloroform. The solution was then titrated with 0.1 M HCl until a pH of 3 was reached. If 20 mL of HCl was required to reach the equivalence point, calculate the number of moles of HCl used.
A. 0.002 mol
Correct B. 0.004 mol
C. 0.006 mol
D. 0.008 mol

Correct Answer: B

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Question 11
Determine the number of unpaired electrons in the ground state of the chromium ion, Cr3+.
Correct A. 1
B. 2
C. 3
D. 4

Correct Answer: A

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Question 12
A 2.5 M solution of sodium hydroxide (NaOH) is mixed with a 1.8 M solution of hydrochloric acid (HCl). What is the resulting concentration of the solution?
A. 1.65 M
Correct B. 2.15 M
C. 2.65 M
D. 3.15 M

Correct Answer: B

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Question 13
What is the major product of the reaction between 2-methylpropene and HCl?
Correct A. 2-chloro-2-methylpropane
B. 2-chloro-2-methylbu\tane
C. 2-chloro-2-methylpen\tane
D. 2-chloro-2-methylhexane

Correct Answer: A

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Question 14
A sample of a metal (X) reacts with oxygen to form a white solid. The reaction is as follows: 4X + 3O2 → 2X2O3. What is the molar mass of the metal (X)?
A. 40 g/mol
Correct B. 60 g/mol
C. 80 g/mol
D. 100 g/mol

Correct Answer: B

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Question 15
A solution of 0.1 M NaOH is mixed with a solution of 0.2 M HCl. What is the pH of the resulting solution?
A. 1
Correct B. 2
C. 3
D. 4

Correct Answer: B

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Question 16
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. If the pH of the solution after the addition of 25.0 mL of NaOH is 8.50, what is the concentration of the NaOH solution?
A. 0.0500 M
B. 0.100 M
Correct C. 0.200 M
D. 0.500 M

Correct Answer: C

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Question 17
A 2.50 g sample of a non-metallic oxide is heated in a stream of hydrogen gas. If the mass of the oxide is reduced to 1.75 g after the reaction, what is the empirical formula of the oxide?
A. O2S
Correct B. SO2
C. SO3
D. S2O3

Correct Answer: B

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Question 18
A 1.00 L sample of a gas at 25°C is collected over water at 25°C. If the partial pressure of the gas is 750 mmHg and the vapor pressure of water is 23.8 mmHg, what is the mole \fraction of the gas?
A. 0.930
B. 0.950
Correct C. 0.970
D. 0.990

Correct Answer: C

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Question 19
A 2.00 g sample of a metal is heated in a stream of oxygen gas. If the mass of the metal is reduced to 1.50 g after the reaction, what is the empirical formula of the metal oxide?
A. MgO
B. CaO
Correct C. Fe2O3
D. CuO

Correct Answer: C

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Question 20
A 1.00 L sample of a gas at 25°C is collected over water at 25°C. If the partial pressure of the gas is 500 mmHg and the vapor pressure of water is 23.8 mmHg, what is the mole \fraction of the gas?
A. 0.850
B. 0.870
Correct C. 0.890
D. 0.910

Correct Answer: C

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Question 21
The polymerization of styrene to polystyrene involves the addition of a monomer to a growing polymer chain. Which of the following is the most likely mechanism for this reaction?
Correct A. Free radical polymerization
B. Cationic polymerization
C. Anionic polymerization
D. Coordination polymerization

Correct Answer: A

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Question 22
A solution of 0.1 M NaCl is prepared by dissolving 6.0 g of NaCl in 100 mL of water. What is the concentration of Na+ ions in the solution?
A. 0.1 M
Correct B. 0.2 M
C. 0.3 M
D. 0.4 M

Correct Answer: B

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Question 23
A sample of air contains 20% O2, 70% N2, and 10% CO2 by volume. What is the partial pressure of O2 in the sample at a total pressure of 1 atm?
Correct A. 0.2 atm
B. 0.3 atm
C. 0.4 atm
D. 0.5 atm

Correct Answer: A

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Question 24
A 2.0 L sample of a solution containing 0.1 M NaCl is electrolyzed u\sing a current of 2.0 A for 5.0 min. What is the mass of Cl2 gas produced at the anode?
A. 0.5 g
Correct B. 1.0 g
C. 1.5 g
D. 2.0 g

Correct Answer: B

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Question 25
A 1.0 M solution of glu\cose (C6H12O6) is prepared by dissolving 36 g of glu\cose in 100 mL of water. What is the concentration of glu\cose in the solution in g/L?
Correct A. 36 g/L
B. 72 g/L
C. 108 g/L
D. 144 g/L

Correct Answer: A

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