POST UTME OAU 2023 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.50 L flask contains 0.500 mol of an ideal gas at 298 K. What is the pressure of the gas in the flask?
A. 1.01 × 10^5 Pa
B. 2.02 × 10^5 Pa
C. 3.03 × 10^5 Pa
D. 4.04 × 10^5 Pa
Question 2
A 10 mL sample of a 0.1 M solution of HCl is titrated with 0.1 M NaOH. What is the pH of the solution after the reaction is complete?
A. 7
B. 8
C. 9
D. 10
Question 3
A 1.0 M solution of HCl is titrated with 1.0 M NaOH. What is the pH of the solution after 50 mL of NaOH has been added?
A. 1.0
B. 2.0
C. 3.0
D. 4.0
Question 4
A 2.5 g sample of a non-metallic oxide is heated in a stream of hydrogen gas. If 1.8 g of water is collected, what is the empirical formula of the oxide?
A. MgO
B. CaO
C. SiO2
D. Al2O3
Question 5
The rate cons\tant (k) for a first-order reaction is given by the equation: k = Ae^\( -Ea/RT \). If the activation energy (Ea) is 100 kJ/mol, the gas cons\tant (R) is 8.314 J/mol*K, and the temperature (T) is 300 K, what is the value of the pre-exponential factor (A) if the rate cons\tant (k) is 0.05 s^-1?
A. 1.23 x 10^6 s^-1
B. 1.23 x 10^7 s^-1
C. 1.23 x 10^8 s^-1
D. 1.23 x 10^9 s^-1
Question 6
A 0.5 M solution of sodium hydroxide (NaOH) is mixed with a 0.5 M solution of hydrochloric acid (HCl). What is the pH of the resulting solution?
A. 1
B. 2
C. 7
D. 14
Question 7
The diagram below shows a titration setup. What is the purpose of the burette in this setup?
A. To measure the volume of the titrant
B. To measure the volume of the analyte
C. To mix the titrant and analyte
D. To measure the pH of the solution
Question 8
A sample of nitrogen gas is collected over water at 25°C and 1 atm. If the partial pressure of water vapor is 0.02 atm, what is the mole \fraction of nitrogen gas?
A. 0.98
B. 0.99
C. 0.995
D. 0.998
Question 9
A 2.5 g sample of a metal is heated in a crucible until it is completely oxidized to its oxide. If the mass of the oxide obtained is 3.2 g, what is the percentage of the metal in the oxide?
A. 78%
B. 80%
C. 85%
D. 90%
Question 10
A 2.5 g sample of a non-metallic oxide is heated in a stream of hydrogen gas. If 1.8 g of water is collected, what is the empirical formula of the oxide?
A. MgO
B. CaO
C. SiO2
D. Al2O3
Question 11
A solution of 0.1 M NaCl is prepared by dissolving 0.1 g of NaCl in 100 mL of water. What is the concentration of the solution in terms of molality?
A. 0.1 m
B. 0.2 m
C. 0.3 m
D. 0.4 m
Question 12
The rate cons\tant (k) 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. 0.005 M
B. 0.01 M
C. 0.02 M
D. 0.03 M
Question 13
The diagram below shows a simple black and white chemistry apparatus showing titration setup. If 25 mL of 0.1 M HCl is added to the burette, what is the concentration of the NaOH solution?
A. 0.05 M
B. 0.1 M
C. 0.2 M
D. 0.5 M
Question 14
What is the electron configuration of the element with atomic number 18?
A. 1s² 2s² 2p⁶ 3s² 3p⁶
B. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
C. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
D. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹
Question 15
A 25 mL sample of 0.5 M H2SO4 is titrated with 1 M NaOH. Calculate the number of moles of NaOH required to reach the equivalence point.
A. 0.05
B. 0.1
C. 0.15
D. 0.2

Master the Exam!

You've seen a preview, but there are thousands more questions plus AI tutor to break down complex solutions.

Unlock Full Access Available for Android & Windows
Help others prepare! Share this practice hub: