POST UTME ACHIEVERS UNIVERSITY 2022 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A colloidal solution of gold (Au) is prepared by the reduction of gold chloride (HAuCl4) u\sing sodium borohydride (NaBH4). What is the name of the process?
A. Precipitation
B. Reduction
C. Nucleation
D. Coagulation
Question 2
Determine the number of moles of oxygen gas (O2) produced when 2.5 moles of hydrogen peroxide (H2O2) decompose according to the equation: 2H2O2(l) → 2H2O(l) + O2(g).
A. 1.25 moles
B. 2.5 moles
C. 3.75 moles
D. 5 moles
Question 3
A redox reaction involves the transfer of electrons from a species with a higher reduction potential to a species with a lower reduction potential. Which of the following reactions represents a redox reaction?
A. 2Na (s) + Cl2 (g) → 2NaCl (s)
B. Ca (s) + 2HCl (aq) → CaCl2 (aq) + H2 (g)
C. 2H2 (g) + O2 (g) → 2H2O (l)
D. Fe (s) + CuSO4 (aq) → FeSO4 (aq) + Cu (s)
Question 4
The s\tandard enthalpy of formation of CO2 is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of H2O?
A. -285.8 kJ/mol
B. -393.5 kJ/mol
C. -483.6 kJ/mol
D. -583.7 kJ/mol
Question 5
A sample of CO2 is collected over water at a temperature of 25°C and a pressure of 1.00 atm. Calculate the partial pressure of CO2 in the gas phase.
A. 0.900 atm
B. 0.950 atm
C. 1.00 atm
D. 1.05 atm
Question 6
A 1.0 M solution of H2SO4 is prepared by dissolving 98.0 g of H2SO4 in water. What is the volume of the solution in liters?
A. 1.0 L
B. 2.0 L
C. 3.0 L
D. 4.0 L
Question 7
The entropy change for the reaction 2NO(g) + O2(g) → 2NO2(g) is -220 J/mol·K. Calculate the s\tandard enthalpy change (ΔH°) for the reaction, given that the s\tandard Gibbs free energy change (ΔG°) is 20 kJ/mol.
A. -200 kJ/mol
B. -220 kJ/mol
C. -240 kJ/mol
D. -260 kJ/mol
Question 8
A 0.1 M solution of NaCl in water is prepared. Calculate the expected molar solubility of NaCl if the solubility product cons\tant (Ksp) is 1.8 x 10^-6. Assume that the density of the solution is 1 g/mL.
A. 0.01 M
B. 0.02 M
C. 0.03 M
D. 0.04 M
Question 9
A 1.0 M solution of sulfuric acid (H2SO4) is mixed with a 1.0 M solution of sodium hydroxide (NaOH). What is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4
Question 10
Calculate the molar mass of a compound that contains 40% carbon and 60% oxygen by mass.
A. 60
B. 80
C. 100
D. 120
Question 11
A 0.500 M solution of NaOH is titrated with a 0.500 M solution of HCl. Calculate the pH of the solution after 25.0 mL of HCl has been added.
A. 2.00
B. 2.50
C. 3.00
D. 3.50
Question 12
A sample of polystyrene (PS) has a density of 1.05 g/cm³ and a molecular weight of 104 g/mol. Calculate the molar volume \( V_m \) of PS.
A. 0.098 m³/mol
B. 0.0985 m³/mol
C. 0.099 m³/mol
D. 0.0995 m³/mol
Question 13
A solution contains 0.100 M CaCl2 and 0.100 M Na2SO4. What is the concentration of Ca2+ ions in the solution?
A. 0.0500 M
B. 0.100 M
C. 0.150 M
D. 0.200 M
Question 14
The diagram below shows a titration setup. Identify the burette.
A.
B.
C.
D.
Question 15
The rate cons\tant for a reaction is 0.05 s^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration after 10 minutes?
A. 0.05 M
B. 0.1 M
C. 0.2 M
D. 0.5 M

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