POST UTME UNILAG 2020 Chemistry | Objective

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Question 1
The reaction of cyclohexane with bromine in the presence of light produces a mixture of 1,2-dibromocyclohexane and 1,4-dibromocyclohexane. What is the major product of this reaction?
A. 1,2-dibromocyclohexane
B. 1,4-dibromocyclohexane
C. cis-1,2-dibromocyclohexane
D. trans-1,2-dibromocyclohexane
Question 2
Calculate the molar enthalpy of vaporization of a subs\tance at 373 K, given that the vapor pressure of the subs\tance at 373 K is 1.01325 bar and the enthalpy of vaporization at 298 K is 40.79 kJ/mol.
A. 43.21 kJ/mol
B. 45.12 kJ/mol
C. 47.03 kJ/mol
D. 49.94 kJ/mol
Question 3
A sample of a polymer is analyzed u\sing gel permeation chromatography (GPC). The chromatogram shows a \single peak with a retention time of 10 minutes. What does this indicate about the polymer?
A. The polymer is a homopolymer
B. The polymer is a copolymer
C. The polymer has a high molecular weight
D. The polymer has a low molecular weight
Question 4
A 0.50 M solution of NaOH is titrated with 0.50 M HCl. What is the pH of the solution after 25.0 mL of HCl has been added?
A. 2.00
B. 3.00
C. 4.00
D. 5.00
Question 5
A diagram of a titration setup is shown below. If 25 mL of 0.1 M NaOH is added to 25 mL of 0.1 M HCl, what is the pH of the resulting solution?
A. 7
B. 8
C. 9
D. 10
Question 6
The diagram below shows a titration setup. 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 add the titrant to the analyte
Question 7
The atomic radius of an atom is defined as the dis\tance from the nucleus to the outermost electron in a neutral atom. Which of the following elements has the largest atomic radius?
A. Hydrogen
B. Helium
C. Lithium
D. Sodium
Question 8
A 1.0 L solution of 0.1 M NaOH is mixed with a 1.0 L solution of 0.1 M HCl. What is the resulting pH?
A. 7
B. 8
C. 9
D. 10
Question 9
A solution of 0.50 M NaOH is mixed with a solution of 0.10 M HCl. What is the concentration of the resulting solution?
A. 0.30 M
B. 0.40 M
C. 0.50 M
D. 0.60 M
Question 10
A solution of 0.20 M NaOH is mixed with a solution of 0.30 M HCl. What is the concentration of the resulting solution?
A. 0.20 M
B. 0.25 M
C. 0.30 M
D. 0.35 M
Question 11
A 2.5 M solution of NaOH is electrolyzed u\sing a platinum electrode. Calculate the mass of oxygen gas produced at the anode after 2 hours.
A. 0.25 g
B. 0.50 g
C. 0.75 g
D. 1.00 g
Question 12
The s\tandard enthalpy of formation of NH3(g) is -45.9 kJ/mol. What is the s\tandard enthalpy of formation of N2(g) if the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol?
A. -45.9 kJ/mol
B. -92.0 kJ/mol
C. -135.9 kJ/mol
D. -180.0 kJ/mol
Question 13
The entropy change (ΔS) for the reaction 2H2(g) + O2(g) → 2H2O(l) is -221.8 J/K. Calculate the s\tandard enthalpy change (ΔH) for the reaction, given that the s\tandard Gibbs free energy change (ΔG) is -237.1 kJ and the temperature (T) is 298 K.
A. -237.1 kJ
B. -237.1 kJ + 298 K * -221.8 J/K
C. -237.1 kJ - 298 K * -221.8 J/K
D. -237.1 kJ + 298 K * 221.8 J/K
Question 14
A redox reaction involves the transfer of electrons from one species to another. Which of the following reactions is an example of a redox reaction?
A. 2H2 + O2 → 2H2O
B. Ca + 2HCl → CaCl2 + H2
C. Fe + CuSO4 → FeSO4 + Cu
D. H2 + Cl2 → 2HCl
Question 15
A 1.00 M solution of NaOH is titrated with 1.00 M HCl. What is the pH of the solution after 25.0 mL of HCl has been added?
A. 2.00
B. 3.00
C. 4.00
D. 5.00

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