POST UTME EKSU 2019 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The reaction: 2NO(g) + O2(g) → 2NO2(g) has a rate cons\tant (k) of 2.50 × 10^\( -3 \) s^\( -1 \) at 298 K. What is the activation energy (Ea) for the reaction?
A. 50.0 kJ/mol
B. 60.0 kJ/mol
C. 70.0 kJ/mol
D. 80.0 kJ/mol
Question 2
A 1.00 M solution of HCl is prepared by dissolving 37.0 g of HCl in 1.00 L of water. What is the concentration of H+ ions in the solution?
A. 0.500 M
B. 0.750 M
C. 1.00 M
D. 1.25 M
Question 3
At 25°C, the vapor pressure of a solution containing 10.0 g of glu\cose (C6H12O6) in 100.0 g of water is 750.0 mmHg. If the vapor pressure of pure water at 25°C is 76.0 mmHg, calculate the mole \fraction of glu\cose in the solution.
A. 0.010
B. 0.020
C. 0.030
D. 0.040
Question 4
The reaction: 2NO(g) + O2(g) → 2NO2(g) has a rate cons\tant (k) of 2.50 × 10^\( -3 \) s^\( -1 \) at 298 K. What is the half-life \( t1/2 \) for the reaction?
A. 1.00 × 10^\( -2 \) s
B. 1.00 × 10^\( -3 \) s
C. 1.00 × 10^\( -4 \) s
D. 1.00 × 10^\( -5 \) s
Question 5
A sample of oxygen gas (O2) occupies a volume of 1.5 L at a pressure of 2.0 atm and a temperature of 298 K. Calculate the number of moles of O2 present.
A. 0.25 mol
B. 0.35 mol
C. 0.45 mol
D. 0.55 mol
Question 6
A solution of sodium hydroxide (NaOH) is titrated with a solution of hydrochloric acid (HCl). If 25 cm^3 of 0.1 M HCl is required to neutralize 20 cm^3 of 0.2 M NaOH, calculate the concentration of the HCl solution.
A. 0.05 M
B. 0.1 M
C. 0.15 M
D. 0.2 M
Question 7
A 2.5 L flask contains 0.5 mol of an ideal gas at 27°C. Calculate the pressure of the gas.
A. 1.5 atm
B. 2.0 atm
C. 2.5 atm
D. 3.0 atm
Question 8
A polymer is a long chain of molecules. What is the repeating unit in the polymer called?
A. Monomer
B. Polymer
C. Repeating unit
D. Chain molecule
Question 9
A 2.0 M solution of sodium carbonate (Na2CO3) is titrated with a 1.0 M solution of hydrochloric acid (HCl). Calculate the volume of HCl required to reach the equivalence point.
A. 200 mL
B. 400 mL
C. 600 mL
D. 800 mL
Question 10
The pH of a solution is 3.5. Calculate the concentration of hydrogen ions \( H+ \) in the solution.
A. 1.0 x 10^-4 M
B. 1.0 x 10^-3 M
C. 1.0 x 10^-2 M
D. 1.0 x 10^-1 M
Question 11
The rate cons\tant for 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 of the reac\tant after 10 minutes?
A. 0.01 M
B. 0.02 M
C. 0.03 M
D. 0.04 M
Question 12
A sample of air contains 21% oxygen, 78% nitrogen, and 1% other gases. What is the partial pressure of oxygen in the air?
A. 0.21 atm
B. 0.21 kPa
C. 21% of total pressure
D. 21% of atmospheric pressure
Question 13
A solution contains 10.0 g of KNO3 in 100.0 g of water. Calculate the molar concentration of the solution.
A. 0.100 M
B. 0.200 M
C. 0.300 M
D. 0.400 M
Question 14
A diagram of a titration setup is shown below. What is the purpose of the burette?
A. To measure the volume of the acid
B. To measure the volume of the base
C. To mix the acid and base
D. To measure the pH of the solution
Question 15
A 50.0-mL sample of a 0.500 M solution of sodium chloride (NaCl) is diluted to a total volume of 100.0 mL. Calculate the new concentration of the solution.
A. 0.250 M
B. 0.500 M
C. 0.750 M
D. 1.00 M

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