POST UTME UNIBEN 2018 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A solution contains 0.500 M HCl and 0.250 M NaOH. What is the pH of the solution after the reaction is complete?
A. 0.500
B. 1.000
C. 1.500
D. 2.000
Question 2
A 250 mL sample of a solution containing 0.100 M NaCl is mixed with 250 mL of a solution containing 0.100 M NaOH. Calculate the concentration of the resulting solution.
A. 0.0500 M
B. 0.100 M
C. 0.150 M
D. 0.200 M
Question 3
A 2.0 g sample of a metal oxide is heated in a crucible until it is completely reduced to the metal. If the mass of the metal produced is 1.5 g, what is the molar mass of the metal oxide?
A. 100 g/mol
B. 150 g/mol
C. 200 g/mol
D. 250 g/mol
Question 4
A metal (X) reacts with oxygen gas to form a brown solid. The reaction is as follows: 4X + 3O_2 → 2X_2O_3. If 2.50 g of X reacts with 1.00 g of O_2, what is the empirical formula of the product?
A. X_2O_3
B. X_2O_4
C. X_2O_5
D. X_2O_6
Question 5
A 2.0 g sample of a metal oxide is heated in a crucible until it is completely reduced to the metal. If the mass of the metal produced is 1.5 g, what is the percentage yield of the reaction?
A. 50%
B. 60%
C. 70%
D. 80%
Question 6
The reaction of zinc with copper(II) sulfate is an example of a ______________ reaction.
A. displacement reaction
B. double displacement reaction
C. precipitation reaction
D. neutralization reaction
Question 7
A sample of hydrogen gas is collected over water at a temperature of 298 K and a pressure of 1.00 atm. If the partial pressure of water vapor is 0.0313 atm, calculate the mole \fraction of hydrogen gas in the sample.
A. 0.999
B. 0.9999
C. 0.99999
D. 0.999999
Question 8
Determine the s\tandard potential of the cell formed by the reaction: MnO4- + 8H+ + 5e- → Mn2+ + 4H2O. Given that the s\tandard potentials of MnO4- and Mn2+ are +1.23 V and -1.18 V, respectively.
A. +1.05 V
B. +1.18 V
C. +1.23 V
D. +1.30 V
Question 9
The solubility of a subs\tance in water is influenced by the ______________ of the subs\tance.
A. molecular weight
B. polarity
C. intermolecular forces
D. temperature
Question 10
What is the pH of a 0.10 M solution of HCl?
A. 0.10
B. 1.0
C. 2.0
D. 3.0
Question 11
A 10 g sample of a polymer is dissolved in 100 mL of solvent. What is the concentration of the polymer solution in g/mL?
A. 0.1 g/mL
B. 0.5 g/mL
C. 1 g/mL
D. 5 g/mL
Question 12
The diagram below shows a titration setup. What is the purpose of the ______________?
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 separate the titrant and analyte
Question 13
A 2.5 L sample of a gas at 27°C and 1.0 atm is collected over water at 25°C. What is the partial pressure of the gas?
A. 0.95 atm
B. 1.0 atm
C. 1.05 atm
D. 1.1 atm
Question 14
A mixture of 2.0 g of NaCl and 1.0 g of KNO3 is dissolved in 100 mL of water. What is the molarity of the solution?
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
Question 15
Determine the molar mass of a gas that occupies 2.5 L at 27°C and 1.0 atm.
A. 20 g/mol
B. 30 g/mol
C. 40 g/mol
D. 50 g/mol

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