POST UTME UNIPORT 2019 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.50 g sample of sulfur is burned in oxygen to produce sulfur dioxide. If 1.25 g of sulfur dioxide is collected, what is the percentage yield of sulfur dioxide?
A. 50%
B. 75%
C. 50%
D. 75%
Question 2
A 2.50 g sample of a polymer is dissolved in 100.0 mL of a solvent. The solution is then diluted to 500.0 mL. What is the concentration of the polymer in the final solution?
A. 0.00500 M
B. 0.0100 M
C. 0.0150 M
D. 0.0200 M
Question 3
A 25 mL sample of a colloidal solution contains 0.5 g of particles. Calculate the concentration of the particles in the solution.
A. 0.02 g/mL
B. 0.04 g/mL
C. 0.06 g/mL
D. 0.08 g/mL
Question 4
Calculate the s\tandard Gibbs free energy change for the reaction: 2Al(s) + 3H2SO4(aq) → Al2(SO4)3(aq) + 3H2(g).
A. -1.2 x 10^3 J/mol
B. -1.2 x 10^3 J/mol
C. -1.2 x 10^3 J/mol
D. -1.2 x 10^3 J/mol
Question 5
A sample of 1.0 g of a polymer is dissolved in 100 mL of a solvent. The osmotic pressure of the solution is found to be 1.5 atm at 25°C. Calculate the molar mass of the polymer.
A. \( M = \frac{RT}{P} \)
B. \( M = \frac{P}{RT} \)
C. \( M = \frac{RT}{P} + \frac{P}{RT} \)
D. \( M = \frac{P}{RT} - \frac{RT}{P} \)
Question 6
A 2.0 M solution of NaOH is mixed with a 2.0 M solution of HCl. The resulting solution is found to be 1.0 M. Calculate the initial concentrations of NaOH and HCl.
A. \( [NaOH]_0 = 1.0 M \) and \( [HCl]_0 = 1.0 M \)
B. \( [NaOH]_0 = 2.0 M \) and \( [HCl]_0 = 2.0 M \)
C. \( [NaOH]_0 = 1.0 M \) and \( [HCl]_0 = 2.0 M \)
D. \( [NaOH]_0 = 2.0 M \) and \( [HCl]_0 = 1.0 M \)
Question 7
A 2.0 g sample of a hydrocarbon is burned in a bomb calorimeter, relea\sing 12.5 kJ of heat. What is the molar mass of the hydrocarbon?
A. 20 g/mol
B. 30 g/mol
C. 40 g/mol
D. 50 g/mol
Question 8
A metal (M) reacts with oxygen to form a basic oxide. The reaction is as follows: 4M + 3O2 → 2MO2. If 2.00 g of M is burned in air, what is the volume of O2 consumed at STP?
A. 1.00 L
B. 2.00 L
C. 3.00 L
D. 4.00 L
Question 9
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. The pH of the solution is measured at various points during the titration. At the equivalence point, the pH is 7.00. What is the concentration of the HCl solution?
A. 0.0500 M
B. 0.0750 M
C. 0.100 M
D. 0.125 M
Question 10
The rate cons\tant of 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 11
The enthalpy of combustion of methane is -890 kJ/mol. What is the enthalpy of combustion of 1 mole of ethane?
A. -1.32 MJ/mol
B. -1.42 MJ/mol
C. -1.52 MJ/mol
D. -1.62 MJ/mol
Question 12
A 2.50 M solution of HCl is mixed with a 1.00 M solution of NaOH. If the reaction is complete, what is the concentration of the resulting solution?
A. 1.25 M
B. 1.50 M
C. 2.00 M
D. 2.50 M
Question 13
A 2.50 g sample of a polymer is dissolved in 100.0 mL of a solvent. The solution is then diluted to 500.0 mL. What is the concentration of the polymer in the final solution?
A. 0.00500 M
B. 0.0100 M
C. 0.0150 M
D. 0.0200 M
Question 14
Determine the s\tandard enthalpy of formation of NH3(g) from the following data: ΔHf(NH3(g)) = ?; ΔHf(H2(g)) = -285.8 kJ/mol; ΔHf(N2(g)) = 0 kJ/mol.
A. -46.1 kJ/mol
B. -92.2 kJ/mol
C. -46.1 kJ/mol
D. -92.2 kJ/mol
Question 15
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. The pH of the solution is measured at various points during the titration. At the equivalence point, the pH is 7.00. What is the pH of the solution when 10.0 mL of NaOH has been added?
A. 4.00
B. 6.00
C. 7.00
D. 9.00

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