POST UTME AFE BABALOLA UNIVERSITY 2025 Chemistry | Objective

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Question 1
A 0.1 M solution of sodium chloride (NaCl) is prepared by dissolving 2.5 g of NaCl in 100 mL of water. What is the concentration of the solution in mol/L?
A. 0.05 M
Correct B. 0.1 M
C. 0.2 M
D. 0.5 M

Correct Answer: B

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Question 2
A diagram of a titration setup is shown below. If 25 mL of 0.1 M HCl is added to 25 mL of 0.1 M NaOH, what is the pH of the resulting solution?
A. 7
B. 9
Correct C. 11
D. 13

Correct Answer: C

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Question 3
A 1 L flask contains 0.5 mol of N2 and 0.5 mol of O2 at 25°C. What is the partial pressure of O2 in the flask?
A. 0.5 atm
Correct B. 1 atm
C. 2 atm
D. 3 atm

Correct Answer: B

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Question 4
A diagram of a simple black and white chemistry apparatus showing a titration setup is shown below. If 25 mL of 0.1 M HCl is added to 25 mL of 0.1 M NaOH, what is the pH of the resulting solution?
A. 7
B. 9
Correct C. 11
D. 13

Correct Answer: C

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Question 5
A 0.1 M solution of sodium chloride (NaCl) is prepared by dissolving 2.5 g of NaCl in 100 mL of water. What is the concentration of the solution in mol/L?
A. 0.05 M
Correct B. 0.1 M
C. 0.2 M
D. 0.5 M

Correct Answer: B

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Question 6
Determine the molecular formula of the compound formed by the reaction of sulfur with oxygen. Given that the balanced equation is \( 2S + 3O_2 \rightarrow 2SO_3 \).
A. SO
B. SO2
Correct C. SO3
D. SO4

Correct Answer: C

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Question 7
A sample of hydrocarbon has a density of 0.65 g/mL and a molar mass of 42 g/mol. What is the empirical formula of the hydrocarbon?
A. CH2
B. CH3
Correct C. C2H4
D. C2H6

Correct Answer: C

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Question 8
A solution of sodium chloride (NaCl) is prepared by dissolving 35.5 g of NaCl in 250 mL of water. What is the molarity 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 9
A mixture of 2.5 g of glu\cose (C6H12O6) and 1.5 g of fructose (C6H12O6) is dissolved in 100 mL of water. What is the osmotic pressure of the solution at 25°C?
A. 1.2 atm
B. 2.5 atm
Correct C. 3.8 atm
D. 4.2 atm

Correct Answer: C

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Question 10
A sample of polystyrene (PS) has a molecular weight of 280,000 g/mol. What is the number of monomer units in the polymer chain?
A. 100
B. 200
C. 500
Correct D. 1000

Correct Answer: D

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Question 11
A 2.5-g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide produced is 2.1 g, calculate the percentage yield of the metal oxide.
A. 80%
B. 85%
Correct C. 90%
D. 95%

Correct Answer: C

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Question 12
A solution of sodium hydroxide (NaOH) is titrated with a solution of hydrochloric acid (HCl). If 25.0 cm³ of the HCl solution is required to neutralize 20.0 cm³ of the NaOH solution, calculate the concentration of the HCl 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 13
A 1.0-g sample of a metal is heated in a crucible until it melts. The mass of the metal oxide produced is 1.2 g. If the metal has a density of 8.0 g/cm³, calculate the volume of the metal oxide produced.
A. 0.15 cm³
B. 0.20 cm³
Correct C. 0.25 cm³
D. 0.30 cm³

Correct Answer: C

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Question 14
A solution of ammonia (NH₃) is added to a solution of hydrochloric acid (HCl) in a titration experiment. If 20.0 cm³ of the NH₃ solution is required to neutralize 30.0 cm³ of the HCl solution, calculate the concentration of the NH₃ solution.
A. 0.2 M
B. 0.3 M
Correct C. 0.4 M
D. 0.5 M

Correct Answer: C

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Question 15
A 2.5-g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide produced is 2.1 g, calculate the percentage yield of the metal oxide.
A. 80%
B. 85%
Correct C. 90%
D. 95%

Correct Answer: C

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Question 16
Determine the pH of a 0.1 M solution of HCl at 25°C. The dissociation cons\tant for HCl is 10^\( -7 \).
A. 1
B. 2
C. 3
Correct D. 4

Correct Answer: D

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Question 17
A 25 mL sample of 0.5 M NaOH is titrated with 0.5 M HCl. Calculate the number of moles of HCl required to reach the equivalence point.
A. 0.0125
B. 0.025
Correct C. 0.0375
D. 0.05

Correct Answer: C

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Question 18
A metal (X) reacts with oxygen to form a basic oxide. The reaction is as follows: 4X + 3O2 → 2X2O3. If 2.5 g of X is heated in air, what is the volume of oxygen required at STP?
A. 1.5 L
B. 2.5 L
Correct C. 3.75 L
D. 5 L

Correct Answer: C

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Question 19
A 2.0 g sample of an organic compound (C6H12O6) is dissolved in 100 mL of water. Calculate the molarity of 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 20
A 1.0 M solution of NaOH is titrated with a 1.0 M solution of HCl. Calculate the pH of the solution at the equivalence point.
Correct A. 7
B. 8
C. 9
D. 10

Correct Answer: A

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Question 21
The reaction of nitrogen dioxide with water produces nitric acid and nitric oxide. Write the balanced chemical equation for this reaction, including the state of each subs\tance.
A. 4NO2 + 2H2O → 4HNO3 + O2
Correct B. 4NO2 + 2H2O → 4HNO3 + 2NO
C. 4NO2 + 2H2O → 4HNO3 + 2O2
D. 4NO2 + 2H2O → 4HNO3 + 4NO

Correct Answer: B

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Question 22
A 2.5 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. The mass of the metal oxide produced is 1.8 g. What is the molar mass of the metal carbonate?
A. 120 g/mol
B. 140 g/mol
Correct C. 160 g/mol
D. 180 g/mol

Correct Answer: C

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Question 23
The half-life of a radioactive subs\tance is 10 years. If a sample of this subs\tance has an initial activity of 100 Bq, what is its activity after 20 years?
A. 50 Bq
B. 25 Bq
C. 12.5 Bq
Correct D. 6.25 Bq

Correct Answer: D

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Question 24
A 1.0 L sample of a gas at 2.0 atm and 25°C is compressed to 4.0 atm and 50°C. What is the new volume of the gas?
A. 0.25 L
Correct B. 0.5 L
C. 1.0 L
D. 2.0 L

Correct Answer: B

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Question 25
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. 9
C. 11
D. 13

Correct Answer: A

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