POST UTME LASU 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
Determine the rate cons\tant (k) for the reaction: 2NO(g) + O2(g) → 2NO2(g), given that the initial concentration of NO is 0.5 M, the initial concentration of O2 is 0.2 M, and after 10 minutes, the concentration of NO2 is 0.4 M. The rate cons\tant (k) is related to the rate cons\tant (k') by the equation: k = k' / \( 1 + k' * t \), where t is the time in minutes.
A. 0.05 min^-1
B. 0.1 min^-1
C. 0.2 min^-1
D. 0.5 min^-1
Question 2
Determine the number of moles of oxygen gas (O2) that will react with 2.50 moles of propane (C3H8) according to the balanced equation: 2C3H8 + 19O2 → 12CO2 + 14H2O.
A. 0.50 mol
B. 1.00 mol
C. 1.50 mol
D. 2.00 mol
Question 3
A 25.0 mL sample of a sulfuric acid solution contains 0.0500 g of sulfuric acid. Calculate the molarity of the solution.
A. 0.100 M
B. 0.200 M
C. 0.500 M
D. 1.00 M
Question 4
A sample of polystyrene has a molecular weight of 280,000 g/mol. If 2.5 g of the polymer is dissolved in 50 mL of toluene, what is the concentration of the solution in g/L?
A. 0.05 g/mL
B. 0.1 g/mL
C. 0.2 g/mL
D. 0.5 g/mL
Question 5
A solution of 0.1 M HCl is titrated with 0.1 M NaOH. What is the pH of the solution after 25 mL of NaOH has been added?
A. 1
B. 2
C. 3
D. 4
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 solution
B. To measure the pH of the solution
C. To mix the solutions
D. To heat the solutions
Question 7
A 2.0 L solution of 0.2 M H2SO4 is mixed with 2.0 L of 0.2 M NaOH. What is the pH of the resulting solution?
A. 2.0
B. 3.0
C. 4.0
D. 5.0
Question 8
Determine the major product of the reaction between 2-methyl-2-propanol and HCl.
A. 2-chloro-2-methylpropane
B. 2-chloro-2-methyl-1-propanol
C. 2-chloro-2-methyl-2-propanol
D. 2-chloro-2-methyl-1-propanol
Question 9
A sample of a hydrocarbon with the molecular formula C5H12 is found to have a density of 0.65 g/mL. Calculate the molar mass of the hydrocarbon.
A. 60 g/mol
B. 70 g/mol
C. 80 g/mol
D. 90 g/mol
Question 10
Determine the number of moles of oxygen gas that will react with 2.50 g of carbon to form carbon dioxide.
A. 0.0500 mol
B. 0.100 mol
C. 0.200 mol
D. 0.500 mol
Question 11
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution after the addition of 25.0 mL of NaOH.
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 12
A 1.0 L solution of 0.1 M NaOH is mixed with 1.0 L of 0.1 M HCl. What is the pH of the resulting solution?
A. 7.0
B. 8.0
C. 9.0
D. 10.0
Question 13
Calculate the equilibrium cons\tant (Kc) for the reaction: N2(g) + 3H2(g) ⇌ 2NH3(g). Given that [N2] = 0.10 M, [H2] = 0.30 M, and [NH3] = 0.20 M.
A. 0.25
B. 0.50
C. 1.00
D. 2.00
Question 14
The diagram below shows a titration setup.
A. The burette contains HCl.
B. The beaker contains NaOH.
C. The burette contains NaOH.
D. The beaker contains HCl.
Question 15
A 0.5 M solution of HCl is titrated with a 0.5 M solution of NaOH. If 25 mL of NaOH is required to reach the equivalence point, what is the pH of the solution at this point?
A. 1
B. 2
C. 7
D. 14

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