POST UTME CHRISTOPHER UNIVERSITY 2025 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A solution contains 0.1 M NaCl and 0.1 M Na2SO4. What is the concentration of Cl- ions in the solution?
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
Question 2
A 0.1 M solution of a weak acid HA \( K_a = 1.8 x 10^\( -5 \ \)) is mixed with a 0.1 M solution of a strong base NaOH. The initial pH of the acid solution is 4.5. What is the pH of the resulting solution after the acid and base have completely reacted?
A. 5.5
B. 6.5
C. 7.5
D. 8.5
Question 3
A 10.0 g sample of a metal carbonate is heated to produce a metal oxide and CO2 gas. If the mass of the metal oxide produced is 7.50 g, what is the molar mass of the metal?
A. 40.0 g/mol
B. 50.0 g/mol
C. 60.0 g/mol
D. 70.0 g/mol
Question 4
A sample of air contains 20.0% O2, 70.0% N2, and 10.0% Ar by volume. What is the partial pressure of O2 in a sample of air at 1.00 atm?
A. 0.20 atm
B. 0.40 atm
C. 0.60 atm
D. 0.80 atm
Question 5
The rate cons\tant (k) 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 6
A 2.5 M solution of HCl is mixed with a 1.0 M solution of NaOH. If the reaction is allowed to go to completion, what is the concentration of the resulting solution?
A. 1.25 M
B. 2.25 M
C. 3.25 M
D. 4.25 M
Question 7
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, and ΔHf(Ca(s)) = -178.2 kJ/mol.
A. -1206.8 kJ/mol
B. -1206.9 kJ/mol
C. -1206.7 kJ/mol
D. -1206.6 kJ/mol
Question 8
The diagram below shows a titration setup for determining the concentration of a strong acid.
A. The acid is a strong acid.
B. The acid is a weak acid.
C. The base is a strong base.
D. The base is a weak base.
Question 9
A 1.00 M solution of NaOH is mixed with a 1.00 M solution of HCl. If the reaction is allowed to go to completion, what is the pH of the resulting solution?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 10
A 0.1 M solution of a weak acid HA \( K_a = 1.8 x 10^\( -5 \ \)) is mixed with a 0.1 M solution of a strong base NaOH. The initial pH of the acid solution is 4.5. What is the pH of the resulting solution after the acid and base have completely reacted?
A. 5.5
B. 6.5
C. 7.5
D. 8.5

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