POST UTME OAU 2019 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The s\tandard electrode potential of the couple Zn2+/Zn is -0.76 V. Calculate the s\tandard electrode potential of the couple Cu2+/Cu, given that the s\tandard electrode potential of the couple Cu2+/Cu is x V.
A. -0.34 V
B. -0.76 V
C. 0.34 V
D. 0.76 V
Question 2
The reaction of zinc metal with copper(II) sulfate solution is represented by the equation: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s). What is the oxidation state of copper in the reac\tant and product?
A. +2 in reac\tant, +2 in product
B. +2 in reac\tant, -2 in product
C. -2 in reac\tant, +2 in product
D. -2 in reac\tant, -2 in product
Question 3
A 2.50 g sample of a non-metallic element is found to have a mass of 1.25 g after being heated in a Bunsen burner. What is the percentage increase in mass?
A. 25.0%
B. 50.0%
C. 75.0%
D. 100.0%
Question 4
A 0.1 M solution of NaCl is electrolyzed u\sing a platinum electrode. Calculate the mass of chlorine gas liberated at the anode after 2 hours, given that the current is 2 A and the cell potential is 2.5 V.
A. 0.5 g
B. 1 g
C. 2 g
D. 5 g
Question 5
A 25 mL sample of 0.2 M H2SO4 is titrated with 0.2 M NaOH. Calculate the volume of NaOH required to reach the equivalence point.
A. 10 mL
B. 20 mL
C. 30 mL
D. 40 mL
Question 6
A diagram of a titration setup is shown below. What is the purpose of the burette?
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 7
A 10% solution of sulfuric acid (H2SO4) is made by dissolving 10 g of the acid in 90 g of water. Calculate the molarity of the solution.
A. 0.1 M
B. 0.5 M
C. 1.0 M
D. 2.0 M
Question 8
The s\tandard electrode potential of the Mn2+/Mn couple is +1.18 V. Calculate the s\tandard electrode potential of the MnO42-/Mn couple.
A. +1.18 V
B. +1.38 V
C. +1.58 V
D. +1.78 V
Question 9
The reaction of hydrogen gas with oxygen to form water is represented by the equation: 2H2 + O2 → 2H2O. What is the value of ΔH for this reaction, given that ΔH for the formation of H2O is -285.8 kJ/mol?
A. -571.6 kJ/mol
B. -285.8 kJ/mol
C. -74.8 kJ/mol
D. -74.8 kJ/mol
Question 10
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 2.50 g of carbon at 298 K.
A. -789 kJ
B. -789.5 kJ
C. -788.5 kJ
D. -790 kJ
Question 11
A metal (M) reacts with chlorine gas (Cl2) to form a white solid. The reaction is as follows: M + Cl2 → MCl2. If 2.5 g of MCl2 is produced, calculate the mass of M used.
A. 1.25 g
B. 2.5 g
C. 3.75 g
D. 5.0 g
Question 12
A 0.5 M solution of NaOH is prepared by dissolving 10 g of NaOH in water to make 1 L of solution. Calculate the concentration of the solution in mol/L.
A. 0.1 M
B. 0.2 M
C. 0.5 M
D. 1.0 M
Question 13
A colloidal solution of starch in water is prepared by adding 2 g of starch to 100 mL of water. The solution is then centrifuged at 3000 rpm for 10 minutes. Calculate the volume of the superna\tant liquid.
A. 50 mL
B. 75 mL
C. 100 mL
D. 125 mL
Question 14
A 2.5 M solution of sodium hydroxide is prepared by dissolving 25 g of sodium hydroxide in water to make 1 L of solution. What is the concentration of sodium ions in the solution?
A. 0.5 M
B. 1.0 M
C. 1.5 M
D. 2.0 M
Question 15
A colloidal solution of starch in water is prepared by boiling the mixture. The resulting solution is stable for 2 hours. What is the type of colloid formed?
A. True solution
B. Colloidal solution
C. Suspension
D. Emulsion

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