POST UTME BOWEN UNIVERSITY 2018 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The s\tandard reduction potential of the couple Zn2+/Zn is -0.76 V. What is the s\tandard cell potential when a zinc electrode is connected to a copper electrode with a s\tandard reduction potential of +0.34 V?
A. -1.10 V
B. -0.76 V
C. 0.58 V
D. 1.10 V
Question 2
A 2 M solution of H2SO4 is titrated with 0.5 M NaOH. Calculate the pH of the solution after 25 mL of NaOH has been added.
A. 1
B. 2
C. 3
D. 4
Question 3
A 250.0 g sample of a subs\tance is found to have a mass of 150.0 g after being placed in a 100.0 mL beaker. What is the density of the subs\tance?
A. 1.5 g/mL
B. 2.0 g/mL
C. 3.0 g/mL
D. 4.0 g/mL
Question 4
The pH of a solution is 4.5. What is the concentration of hydrogen ions \( H+ \) in the solution?
A. 1.0 × 10^-5 M
B. 1.0 × 10^-4 M
C. 1.0 × 10^-3 M
D. 1.0 × 10^-6 M
Question 5
The s\tandard enthalpy of formation of carbon dioxide (CO2) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of carbon monoxide (CO)?
A. -110.5 kJ/mol
B. -130.5 kJ/mol
C. -150.5 kJ/mol
D. -170.5 kJ/mol
Question 6
A 2.50-g sample of a metal oxide is heated in a stream of hydrogen gas. The mass of the metal obtained after reduction is 1.75 g. What is the percentage of the metal in the oxide?
A. 40.0%
B. 60.0%
C. 70.0%
D. 80.0%
Question 7
A diagram of a titration setup is shown below.
A. The burette contains the acid.
B. The beaker contains the acid.
C. The test tube contains the acid.
D. The burette contains the base.
Question 8
The s\tandard enthalpy of formation of NH3(g) is -45.9 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of ammonia at 298 K.
A. -45.9 kJ
B. -45.9 kJ/mol
C. -45.9 kJ/g
D. -45.9 kJ/mol NH_3(g)
Question 9
A 0.1 M solution of AgNO3 is electrolyzed u\sing a platinum electrode. Calculate the mass of silver deposited after 2 hours at a current of 2.5 A.
A. 0.25 g
B. 0.5 g
C. 1 g
D. 1.5 g
Question 10
A sample of a polymer has a molecular weight of 20,000 g/mol. If the polymer has a degree of polymerization (DP) of 100, what is the molecular weight of the repeating unit?
A. 200 g/mol
B. 20 g/mol
C. 100 g/mol
D. 50 g/mol
Question 11
A reaction has a ΔH value of -50 kJ/mol and a ΔS value of 100 J/mol·K. At what temperature will the reaction be at equilibrium?
A. 298 K
B. 298.15 K
C. 300 K
D. 300.15 K
Question 12
A reaction is carried out at cons\tant pressure and temperature. The reaction is exothermic and has a negative ΔH value. Which of the following statements is correct?
A. The reaction is spon\taneous.
B. The reaction is non-spon\taneous.
C. The reaction is at equilibrium.
D. The reaction has a positive ΔS value.
Question 13
A diagram of a titration setup is shown below. What is the purpose of the burette?
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 14
A solution contains 0.2 M HCl and 0.2 M NaOH. What is the concentration of H+ ions in the solution after mixing?
A. 0.2 M
B. 0.4 M
C. 0.1 M
D. 0.3 M
Question 15
The half-life of a radioactive subs\tance is 5 years. If 100 g of the subs\tance is present initially, how much will remain after 15 years?
A. 12.5 g
B. 25 g
C. 50 g
D. 100 g

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