POST UTME OAU 2025 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
Determine the pH of a 0.1 M solution of HCl.
A. 1
B. 2
C. 3
D. 4
Question 2
A 2.0 L flask contains 0.50 g of CO at a temperature of 298 K. What is the pressure of the gas?
A. 2.0 atm
B. 3.0 atm
C. 4.0 atm
D. 5.0 atm
Question 3
A 0.5 M solution of NaCl is prepared by dissolving 25 g of NaCl in 1000 mL of water. Calculate the number of moles of NaCl dissolved.
A. 2.5 x 10^-4 mol
B. 5.0 x 10^-4 mol
C. 7.5 x 10^-4 mol
D. 1.0 x 10^-3 mol
Question 4
A 2.0 g sample of a metal is heated in a crucible until it is completely oxidized. The mass of the crucible and the oxide is 4.2 g. What is the mass of the metal that was oxidized?
A. 1.2 g
B. 1.5 g
C. 1.8 g
D. 2.0 g
Question 5
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of H2O(l) if the s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol and the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol?
A. -285.8 kJ/mol
B. -285.9 kJ/mol
C. -286.0 kJ/mol
D. -286.1 kJ/mol
Question 6
The diagram below shows a circuit setup. Identify the part labeled A.
A. Resistor
B. Battery
C. Switch
D. Ammeter
Question 7
A 0.5 M solution of H2SO4 is prepared by dissolving 50 g of H2SO4 in 1000 mL of water. Calculate the number of moles of H2SO4 dissolved.
A. 2.5 x 10^-4 mol
B. 5.0 x 10^-4 mol
C. 7.5 x 10^-4 mol
D. 1.0 x 10^-3 mol
Question 8
A sample of H2 gas is collected over water at a temperature of 25°C and a pressure of 1 atm. If the vapor pressure of water at 25°C is 23.8 mmHg, what is the partial pressure of H2?
A. 736.2 mmHg
B. 712.4 mmHg
C. 688.6 mmHg
D. 664.8 mmHg
Question 9
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of H2O(l) if the s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol and the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol?
A. -285.8 kJ/mol
B. -285.9 kJ/mol
C. -286.0 kJ/mol
D. -286.1 kJ/mol
Question 10
A 0.5 M solution of H2SO4 is prepared by dissolving 9.0 g of H2SO4 in water to make 1 L of solution. What is the concentration of H+ ions in the solution?
A. 0.18 M
B. 0.36 M
C. 0.54 M
D. 0.72 M
Question 11
A 2.50 M solution of HCl is mixed with a 1.00 M solution of NaOH. What is the concentration of the resulting solution?
A. 1.75 M
B. 2.25 M
C. 2.50 M
D. 3.00 M
Question 12
Determine the pH of a 0.1 M solution of HCl, given that the dissociation cons\tant of HCl is 10^\( -7 \) and the dissociation cons\tant of H2O is 10^\( -14 \).
A. 1
B. 2
C. 3
D. 4
Question 13
A sample of CO2 gas is collected over water at a temperature of 25°C and a pressure of 1 atm. If the vapor pressure of water at 25°C is 23.8 mmHg, what is the partial pressure of CO2?
A. 760 mmHg
B. 736.2 mmHg
C. 712.4 mmHg
D. 688.6 mmHg
Question 14
A 0.50 M solution of NaOH is prepared by dissolving 4.0 g of NaOH in water to make 1 L of solution. What is the concentration of OH- ions in the solution?
A. 0.10 M
B. 0.20 M
C. 0.30 M
D. 0.40 M
Question 15
A 1.00 M solution of $\text{H}_2\text{SO}_4$ is mixed with a 2.00 M solution of $\text{BaCl}_2$. What is the concentration of the resulting solution?
A. 0.50
B. 1.00
C. 1.50
D. 2.00

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