POST UTME LEAD CITY UNIVERSITY 2025 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 0.1 M solution of a weak base, B, is titrated with 0.1 M HCl. The initial pH of the base is 9.5. If 20 mL of 0.1 M HCl is added to 80 mL of the base, what is the pH of the resulting solution?
A. 7.5
B. 8.5
C. 9.5
D. 10.5
Question 2
A 25.0-mL sample of a solution containing $\text{Fe}^{2+}$ ions is mixed with 25.0 mL of a solution containing $\text{SCN}^{-}$ ions. If the resulting solution is purple, what is the concentration of $\text{Fe}^{2+}$ ions in the original solution?
A. 0.100 M
B. 0.200 M
C. 0.300 M
D. 0.400 M
Question 3
A 2.5 M solution of sulfuric acid is diluted to 1 M. What is the volume of the solution that needs to be added to 250 mL of the 2.5 M solution to achieve the desired concentration?
A. 125 mL
B. 250 mL
C. 375 mL
D. 500 mL
Question 4
A 2.50 L sample of an ideal gas at 27°C and 1.00 atm is heated to 127°C at cons\tant volume. What is the final pressure of the gas?
A. 2.50 atm
B. 3.00 atm
C. 4.00 atm
D. 5.00 atm
Question 5
A 10 g sample of a subs\tance is found to have a mass of 12 g after being heated in a furnace. What is the percentage increase in mass?
A. 10%
B. 20%
C. 30%
D. 40%
Question 6
A 50.0-mL sample of a solution containing $\text{Na}_2\text{SO}_4$ is mixed with 50.0 mL of a solution containing $\text{BaCl}_2$. If the resulting solution is colorless, what is the concentration of $\text{Na}_2\text{SO}_4$ in the original solution?
A. 0.100 M
B. 0.200 M
C. 0.300 M
D. 0.400 M
Question 7
A 1.0 M solution of a weak acid, HA, is titrated with 1.0 M NaOH. The initial pH of the acid is 3.5. If 20 mL of 1.0 M NaOH is added to 80 mL of the acid, what is the pH of the resulting solution?
A. 6.5
B. 7.5
C. 8.5
D. 9.5
Question 8
The reaction of nitrogen dioxide with water produces nitric acid and nitric oxide. Write the balanced chemical equation for this reaction, including the correct coefficients.
A. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow 2\text{HNO}_3 + \text{NO}
B. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_3 + 2\text{NO}
C. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow 2\text{HNO}_3 + 2\text{NO}
D. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_3 + \text{NO}_2
Question 9
The rate cons\tant for a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration after 10 minutes?
A. 0.01 M
B. 0.02 M
C. 0.03 M
D. 0.04 M
Question 10
A 100.0-mL sample of a solution containing $\text{H}_2\text{SO}_4$ is mixed with 100.0 mL of a solution containing $\text{NaOH}$. If the resulting solution is colorless, what is the concentration of $\text{H}_2\text{SO}_4$ in the original solution?
A. 0.100 M
B. 0.200 M
C. 0.300 M
D. 0.400 M
Question 11
A metal M reacts with chlorine gas to form a white solid product. The reaction is as follows: [ 2M + Cl_2 \rightarrow 2MCl ]. If 2.5 g of M reacts with 1.5 g of Cl_2, what is the percentage yield of the reaction?
A. 50%
B. 60%
C. 70%
D. 80%
Question 12
The s\tandard enthalpy of formation (ΔHf°) for aluminum oxide (Al2O3) is -1675 kJ/mol. What is the s\tandard enthalpy of formation for aluminum (Al) if the s\tandard enthalpy of formation for oxygen gas (O2) is 0 kJ/mol?
A. -1675 kJ/mol
B. -167 kJ/mol
C. 1675 kJ/mol
D. 167 kJ/mol
Question 13
A sample of nitrogen gas occupies a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 300 K. What is the number of moles of nitrogen gas present?
A. 0.05 mol
B. 0.1 mol
C. 0.15 mol
D. 0.2 mol
Question 14
A sample of nitrogen gas (N2) is collected over water at a temperature of 25°C and a pressure of 1 atm. Calculate the partial pressure of N2 in the gas mixture.
A. 0.95 atm
B. 0.99 atm
C. 1.03 atm
D. 1.07 atm
Question 15
A diagram of a titration setup is shown below. If 25.0 mL of 0.100 M NaOH is required to reach the equivalence point, what is the concentration of the HCl solution?
A. 0.0500 M
B. 0.100 M
C. 0.200 M
D. 0.500 M

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