POST UTME ACHIEVERS UNIVERSITY 2020 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 100.0-mL sample of a 0.100 M NaOH solution is mixed with a 100.0-mL sample of a 0.100 M HCl solution. What is the pH of the resulting solution?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 2
A 2.50-g sample of a metal oxide is heated in a crucible until it decomposes completely. If 1.25 g of oxygen is collected, what is the empirical formula of the metal oxide?
A. FeO
B. Fe2O3
C. Fe3O4
D. FeO2
Question 3
A solution contains 2.50 g of NaCl in 100.0 mL of water. What is the molarity of the solution?
A. 0.100 M
B. 0.200 M
C. 0.300 M
D. 0.400 M
Question 4
A metal rod is heated to 800°C and then quenched in water. The resulting metal is then annealed at 300°C for 2 hours. What is the final microstructure of the metal?
A. Ferrite
B. Pearlite
C. Martensite
D. Bainite
Question 5
A 0.1 M solution of a weak acid, HA, is titrated with 0.1 M NaOH. The pH of the solution at the equivalence point is 7. Calculate the pKa of the acid.
A. 1
B. 2
C. 3
D. 4
Question 6
A 500.0-mL sample of a 0.100 M NaOH solution is mixed with a 500.0-mL sample of a 0.100 M HCl solution. What is the pH of the resulting solution?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 7
A 200.0-mL sample of a 0.100 M NaOH solution is mixed with a 200.0-mL sample of a 0.100 M HCl solution. What is the pH of the resulting solution?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 8
Determine the molar mass of a compound that contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass.
A. 12.0 g/mol
B. 24.0 g/mol
C. 36.0 g/mol
D. 48.0 g/mol
Question 9
A reaction has a rate cons\tant (k) of 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration of the reac\tant after 10 minutes?
A. 0.05 M
B. 0.10 M
C. 0.15 M
D. 0.20 M
Question 10
A 2.5 L flask contains 0.5 mol of an ideal gas at 25°C. What is the pressure of the gas?
A. 1.0 atm
B. 2.0 atm
C. 2.5 atm
D. 3.0 atm
Question 11
A 0.5 M solution of sodium hydroxide (NaOH) is prepared by dissolving 10.0 g of NaOH in 1.0 L of water. What is the concentration of the solution in terms of molarity?
A. 0.1 M
B. 0.5 M
C. 1.0 M
D. 2.0 M
Question 12
The half-life of a radioactive subs\tance is 3.00 days. If 150.0 mg of the subs\tance is present initially, how much will remain after 15.0 days?
A. 37.5 mg
B. 75.0 mg
C. 112.5 mg
D. 150.0 mg
Question 13
A sample of air contains 21.0% O2 by volume. If 2.50 L of air is collected, how many moles of O2 are present?
A. 0.0210 mol
B. 0.0420 mol
C. 0.0630 mol
D. 0.0840 mol
Question 14
A sample of a gas occupies a volume of 2.50 L at a temperature of 25°C and a pressure of 1.00 atm. If the temperature is increased to 50°C and the pressure is increased to 2.00 atm, what is the new volume of the gas?
A. 3.00 L
B. 3.50 L
C. 4.00 L
D. 4.50 L
Question 15
A sample of air contains 21.0% O2 by volume. If 5.00 L of air is collected, how many moles of O2 are present?
A. 0.105 mol
B. 0.210 mol
C. 0.315 mol
D. 0.420 mol

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