POST UTME BSU 2021 Chemistry | Objective

Are you preparing for POST UTME BSU exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2021 Chemistry (Objective) questions designed to simulate the real exam environment.

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Question 1
The solubility of a subs\tance in water is 2.5 g/L at 25°C. If 50 mL of water is used to dissolve 1.25 g of the subs\tance, what is the concentration of the solution in g/L?
A. 1.25 g/L
Correct B. 2.5 g/L
C. 5.0 g/L
D. 10.0 g/L

Correct Answer: B

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Question 2
A solution of 0.1 M NaOH is titrated with 0.1 M HCl. If 20 mL of HCl is required to reach the equivalence point, what is the volume of NaOH required to reach the equivalence point?
A. 10 mL
Correct B. 20 mL
C. 30 mL
D. 40 mL

Correct Answer: B

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Question 3
A polymer 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. 200 g/mol
B. 400 g/mol
Correct C. 500 g/mol
D. 1000 g/mol

Correct Answer: C

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Question 4
A solution of 0.1 M NaOH is titrated with 0.1 M HCl. If 20 mL of HCl is required to reach the equivalence point, what is the pH of the solution at the equivalence point?
A. 7
Correct B. 8
C. 9
D. 10

Correct Answer: B

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Question 5
A diagram of a titration setup is shown below. If 20 mL of HCl is required to reach the equivalence point, what is the volume of NaOH required to reach the equivalence point?
A. 10 mL
Correct B. 20 mL
C. 30 mL
D. 40 mL

Correct Answer: B

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Question 6
A 2.50-g sample of a polymer is dissolved in 25.0 mL of a solvent. If the molar mass of the polymer is 500 g/mol, what is the number of moles of the polymer dissolved?
A. 0.0050 mol
Correct B. 0.0100 mol
C. 0.0150 mol
D. 0.0200 mol

Correct Answer: B

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Question 7
A reaction is represented by the equation: 2A + B → C + 3D. If 2.00 mol of A and 1.50 mol of B are present, what is the limiting reac\tant?
A. A
Correct B. B
C. C
D. D

Correct Answer: B

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Question 8
A solution contains 0.100 M NaCl. What is the concentration of Cl- ions in the solution?
A. 0.0500 M
Correct B. 0.100 M
C. 0.150 M
D. 0.200 M

Correct Answer: B

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Question 9
A 1.00-L sample of a gas at 25.0°C and 1.00 atm is collected over water. If the vapor pressure of water at 25.0°C is 23.8 mmHg, what is the partial pressure of the gas?
A. 0.970 atm
Correct B. 0.990 atm
C. 1.00 atm
D. 1.10 atm

Correct Answer: B

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Question 10
A 2.00-g sample of a subs\tance is dissolved in 25.0 mL of a solvent. If the molar mass of the subs\tance is 200 g/mol, what is the concentration of the solution?
A. 0.100 M
Correct B. 0.200 M
C. 0.300 M
D. 0.400 M

Correct Answer: B

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Question 11
A sample of a metal oxide, M2O3, has a mass of 25.0 g. If the molar mass of M2O3 is 228.0 g/mol, calculate the number of moles of M2O3 present in the sample.
A. 0.11 mol
Correct B. 0.22 mol
C. 0.33 mol
D. 0.44 mol

Correct Answer: B

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Question 12
A solution of NaCl is prepared by dissolving 35.5 g of NaCl in 250 mL of water. Calculate the molarity of the solution.
A. 0.15 M
B. 0.25 M
Correct C. 0.35 M
D. 0.45 M

Correct Answer: C

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Question 13
A 2.50 L sample of a gas at 27°C and 1.00 atm is collected over water. If the vapor pressure of water at 27°C is 0.0313 atm, calculate the partial pressure of the gas.
Correct A. 0.968 atm
B. 1.00 atm
C. 1.03 atm
D. 1.05 atm

Correct Answer: A

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Question 14
A 25.0 mL sample of a solution containing 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the number of moles of HCl present in the sample.
A. 0.0025 mol
Correct B. 0.0050 mol
C. 0.0075 mol
D. 0.0100 mol

Correct Answer: B

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Question 15
A metal, M, has a density of 11.5 g/cm³ and a molar mass of 55.9 g/mol. Calculate the number of moles of M present in a 25.0 g sample.
A. 0.44 mol
Correct B. 0.55 mol
C. 0.66 mol
D. 0.77 mol

Correct Answer: B

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Question 16
Determine the oxidation state of nitrogen in the compound NO2.
A. +1
B. +2
Correct C. +3
D. +4

Correct Answer: C

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Question 17
A 2.5 M solution of NaOH is mixed with a 2.5 M solution of HCl. What is the resulting pH?
A. 1
Correct B. 7
C. 10
D. 14

Correct Answer: B

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Question 18
A 10 mL sample of a 0.1 M solution of FeCl3 is mixed with a 10 mL sample of a 0.1 M solution of NaOH. What is the resulting concentration of Fe(OH)3?
A. 0.01 M
Correct B. 0.02 M
C. 0.03 M
D. 0.04 M

Correct Answer: B

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Question 19
A 1 L sample of a 0.5 M solution of H2SO4 is mixed with a 1 L sample of a 0.5 M solution of NaOH. What is the resulting concentration of H2O?
A. 0.25 M
Correct B. 0.5 M
C. 0.75 M
D. 1 M

Correct Answer: B

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Question 20
A 5 mL sample of a 0.1 M solution of CaCl2 is mixed with a 5 mL sample of a 0.1 M solution of NaOH. What is the resulting concentration of Ca(OH)2?
A. 0.005 M
Correct B. 0.01 M
C. 0.015 M
D. 0.02 M

Correct Answer: B

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Question 21
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) = 0 kJ/mol.
Correct A. -1206.60 kJ/mol
B. -1206.20 kJ/mol
C. -1206.40 kJ/mol
D. -1206.80 kJ/mol

Correct Answer: A

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Question 22
A 2.50 L flask contains 0.500 mol of an ideal gas at 25°C. Calculate the pressure of the gas.
Correct A. 1.01 × 10^5 Pa
B. 2.01 × 10^5 Pa
C. 3.01 × 10^5 Pa
D. 4.01 × 10^5 Pa

Correct Answer: A

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Question 23
A solution contains 0.100 M HCl and 0.0500 M NaOH. What is the pH of the resulting solution?
A. 2.00
Correct B. 3.00
C. 4.00
D. 5.00

Correct Answer: B

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Question 24
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. What is the pH of the resulting solution after 25.0 mL of NaOH has been added?
A. 2.00
Correct B. 3.00
C. 4.00
D. 5.00

Correct Answer: B

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Question 25
A 2.00 L flask contains 0.500 mol of an ideal gas at 25°C. What is the volume of the gas at 50°C?
A. 1.00 L
Correct B. 2.00 L
C. 3.00 L
D. 4.00 L

Correct Answer: B

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