POST UTME ELIZADE UNIVERSITY 2018 Chemistry | Objective

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Question 1
A solution of sodium hydroxide is titrated with a solution of hydrochloric acid. The initial pH of the sodium hydroxide solution is 12.0. After the addition of 30.0 mL of hydrochloric acid, the pH of the solution is 9.0. What is the concentration of the hydrochloric acid solution?
A. 0.050 M
B. 0.100 M
C. 0.200 M
D. 0.500 M
Question 2
A redox reaction is represented by the equation: 2Fe^{2+} + MnO_4^- + 6H^+ → 2Fe^{3+} + Mn^{2+} + 3H_2O. What is the oxidation state of the manganese ion in the product?
A. +2
B. +3
C. +4
D. +5
Question 3
A 5.0 M solution of HCl is mixed with a 2.0 M solution of NaOH. What is the resulting concentration of the solution after the reaction is complete?
A. 2.5 M
B. 3.0 M
C. 3.75 M
D. 5.0 M
Question 4
A 0.100 M solution of NaOH is mixed with a 0.100 M solution of HCl. What is the concentration of NaOH in the resulting solution?
A. 0.0500 M
B. 0.0500 M
C. 0.0500 M
D. 0.0500 M
Question 5
The rate cons\tant for the decomposition of N2O5 is 2.50 × 10^\( -3 \) s^\( -1 \) at 298 K. What is the half-life of the reaction?
A. 277 s
B. 278 s
C. 279 s
D. 280 s
Question 6
The reaction of benzene with bromine is as follows: C6H6 + Br2 → C6H6Br2. If 1.00 mol of benzene reacts with 1.00 mol of bromine, what is the product formed?
A. C6H6
B. Br2
C. C6H6Br2
D. H2O
Question 7
A solution of sodium hydroxide is titrated with a solution of hydrochloric acid. The initial pH of the sodium hydroxide solution is 12.0. After the addition of 20.0 mL of hydrochloric acid, the pH of the solution is 10.0. What is the concentration of the hydrochloric acid solution?
A. 0.050 M
B. 0.100 M
C. 0.200 M
D. 0.500 M
Question 8
A 0.100 M solution of HCl is titrated with 0.100 M NaOH. What is the pH of the solution after 25.0 mL of NaOH has been added?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 9
The reaction of ethanol with sulfuric acid is as follows: C2H5OH + H2SO4 → C2H5OSO3H + H2O. If 1.00 mol of ethanol reacts with 1.00 mol of sulfuric acid, what is the product formed?
A. C2H5OH
B. H2SO4
C. C2H5OSO3H
D. H2O
Question 10
The s\tandard enthalpy of formation (ΔHf°) for CO2(g) is -393.5 kJ/mol. The s\tandard enthalpy of formation (ΔHf°) for H2O(l) is -285.8 kJ/mol. Calculate the s\tandard enthalpy of formation (ΔHf°) for the reaction: CO(g) + H2(g) → CO2(g) + H2O(l).
A. -679.3 kJ/mol
B. -679.3 kJ/mol + 393.5 kJ/mol
C. -679.3 kJ/mol - 393.5 kJ/mol
D. -679.3 kJ/mol + 285.8 kJ/mol
Question 11
A solution of sodium hydroxide is titrated with a solution of hydrochloric acid. The initial pH of the sodium hydroxide solution is 12.0. After the addition of 25.0 mL of hydrochloric acid, the pH of the solution is 10.5. What is the concentration of the hydrochloric acid solution?
A. 0.100 M
B. 0.200 M
C. 0.500 M
D. 1.00 M
Question 12
A 0.1 M solution of a weak acid (HA) is 10% ionized at 25°C. If the dissociation cons\tant (Ka) of the acid is 1.0 x 10^-5, calculate the pH of the solution.
A. 2.0
B. 2.5
C. 3.0
D. 3.5
Question 13
A 0.500 M solution of NaOH is mixed with a 0.500 M solution of HCl. Calculate the pH of the resulting solution.
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 14
Determine the molar mass of a polymer with the following composition: 60% polyethylene (C2H4), 20% polypropylene (C3H6), and 20% polystyrene (C8H8).
A. 60 g/mol
B. 120 g/mol
C. 180 g/mol
D. 240 g/mol
Question 15
A sample of a polymer is analyzed u\sing gel permeation chromatography (GPC). The chromatogram shows a \single peak with a retention time of 12.5 minutes. What is the molecular weight of the polymer?
A. 10,000 g/mol
B. 50,000 g/mol
C. 100,000 g/mol
D. 500,000 g/mol

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