POST UTME NILE UNIVERSITY 2025 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A solution of sodium chloride (NaCl) is prepared by dissolving 10 g of NaCl in 100 mL of water. What is the molarity of the solution?
A. 0.1 M
B. 0.5 M
C. 1.0 M
D. 2.0 M
Question 2
The s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol. Calculate the s\tandard enthalpy of formation of H2(g) if the s\tandard enthalpy of formation of H2O(g) is -241.8 kJ/mol and that of O2(g) is 0 kJ/mol.
A. 0 kJ/mol
B. -110.5 kJ/mol
C. -241.8 kJ/mol
D. -241.8 kJ/mol - 110.5 kJ/mol
Question 3
Determine the rate cons\tant (k) for the reaction: N2O5 → 2NO2 + 1/2O2, given that the initial concentration of N2O5 is 0.1 M and the concentration after 10 minutes is 0.05 M. The rate cons\tant is related to the half-life \( t1/2 \) by the equation: k = ln(2)/t1/2.
A. 0.05 min^-1
B. 0.1 min^-1
C. 0.2 min^-1
D. 0.5 min^-1
Question 4
A 0.1 M solution of sodium hydroxide is mixed with a 0.1 M solution of hydrochloric acid. What is the pH of the resulting solution?
A. 5
B. 6
C. 7
D. 8
Question 5
A 2.0 L flask contains 0.5 mol of an ideal gas at 298 K. Calculate the temperature of the gas u\sing the ideal gas law: PV = nRT.
A. 298 K
B. 298.5 K
C. 299 K
D. 300 K
Question 6
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of H2O(g) if the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol and that of O2(g) is 0 kJ/mol.
A. -241.8 kJ/mol
B. -241.0 kJ/mol
C. -240.5 kJ/mol
D. -239.5 kJ/mol
Question 7
The diagram below shows a titration setup. What is the purpose of the burette in this setup?
A. To measure the volume of the titrant
B. To measure the volume of the analyte
C. To mix the titrant and analyte
D. To separate the titrant and analyte
Question 8
A sample of a polymer has a molecular weight of 100,000 g/mol. If 2.5 g of the polymer is dissolved in 25 mL of a solvent, what is the concentration of the solution in g/L?
A. 50
B. 75
C. 100
D. 125
Question 9
A 1.0 M solution of potassium chloride is mixed with a 1.0 M solution of sodium hydroxide. What is the resulting solution?
A. NaCl(aq) + KCl(aq)
B. NaOH(aq) + KCl(aq)
C. NaCl(aq) + KCl(aq)
D. NaOH(aq) + KCl(aq)
Question 10
A diagram of a titration setup is shown below. What is the purpose of the burette in this setup?
A. To measure the volume of the analyte
B. To measure the volume of the titrant
C. To measure the pH of the solution
D. To measure the temperature of the solution
Question 11
A 2.5 L flask contains 0.5 mol of an ideal gas at 298 K. Calculate the pressure of the gas u\sing the ideal gas law: PV = nRT.
A. 101325 Pa
B. 202650 Pa
C. 303875 Pa
D. 405100 Pa
Question 12
A solution contains 0.1 M NaCl and 0.2 M NaOH. Calculate the pH of the solution u\sing the equation: pH = -\log[H+].
A. 1
B. 2
C. 3
D. 4
Question 13
A 0.1 M solution of H2SO4 is titrated with 0.1 M NaOH. If 20 mL of H2SO4 is required to reach the equivalence point, what is the pH of the solution at the equivalence point?
A. 1
B. 2
C. 3
D. 4
Question 14
A sample of a salt is dissolved in water to give a solution with a pH of 7. What is the nature of the salt?
A. Acidic
B. Basic
C. Neutral
D. Amphoteric
Question 15
A solution of HCl is 0.1 M. If 10 mL of this solution is titrated with 0.1 M NaOH, what is the pH of the solution after the titration?
A. 1
B. 2
C. 3
D. 4

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