POST UTME AFE BABALOLA UNIVERSITY 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.0 L flask contains 1.0 M $\text{CO}_2$ at 25°C. If 1.0 L of $\text{N}_2$ is added to the flask, what is the new partial pressure of $\text{CO}_2$?
A. 0.5 atm
B. 1.0 atm
C. 1.5 atm
D. 2.0 atm
Question 2
The following diagram shows a titration setup. Identify the part labeled A.
A. Burette
B. Beaker
C. Test tube
D. Circuit
Question 3
The half-life of a radioactive subs\tance is 5.0 years. If 100.0 mg of the subs\tance is initially present, what is the mass of the subs\tance remaining after 20.0 years?
A. 12.5 mg
B. 25.0 mg
C. 50.0 mg
D. 100.0 mg
Question 4
A polymer has the following structure: [-CH2-CH2-CH2-CH2-]n. What is the type of polymerization reaction that produced this polymer?
A. Addition polymerization
B. Condensation polymerization
C. Ring-opening polymerization
D. Step-growth polymerization
Question 5
A solution contains 0.1 M NaCl and 0.1 M Na2SO4. Calculate the total concentration of ions in the solution.
A. 0.2 M
B. 0.3 M
C. 0.4 M
D. 0.5 M
Question 6
A 2.0 g sample of a polymer is dissolved in 100 mL of solvent. Calculate the molar mass of the polymer.
A. 500 g/mol
B. 600 g/mol
C. 700 g/mol
D. 800 g/mol
Question 7
A 2.0 g sample of a metal is heated in air to produce a metal oxide. If the mass of the metal oxide is 2.5 g, calculate the percentage increase in mass.
A. 10%
B. 20%
C. 30%
D. 40%
Question 8
A redox reaction involves the oxidation of Fe2+ to Fe3+ and the reduction of MnO4- to Mn2+. Write the balanced equation for the reaction.
A. \[ \text{Fe}^{2+} + \text{MnO}_4^- + 4\text{H}^+ \rightarrow \text{Fe}^{3+} + \text{Mn}^{2+} + 2\text{H}_2\text{O} \]
B. \[ \text{Fe}^{2+} + \text{MnO}_4^- + 2\text{H}^+ \rightarrow \text{Fe}^{3+} + \text{Mn}^{2+} + \text{H}_2\text{O} \]
C. \[ \text{Fe}^{2+} + \text{MnO}_4^- + 3\text{H}^+ \rightarrow \text{Fe}^{3+} + \text{Mn}^{2+} + \text{H}_2\text{O} \]
D. \[ \text{Fe}^{2+} + \text{MnO}_4^- + 5\text{H}^+ \rightarrow \text{Fe}^{3+} + \text{Mn}^{2+} + 2\text{H}_2\text{O} \]
Question 9
Calculate the s\tandard enthalpy change (ΔH⁰) for the reaction: 2Al(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2(g). The s\tandard enthalpy of formation (ΔH⁰f) values are: Al(s) = 0 kJ/mol, HCl(aq) = -92.3 kJ/mol, AlCl3(aq) = -704.0 kJ/mol, H2(g) = 0 kJ/mol. Assume the reaction is carried out at 298 K.
A. -1768.6 kJ/mol
B. -704.0 kJ/mol
C. -92.3 kJ/mol
D. -704.0 kJ/mol + 2\( 0 kJ/mol \)
Question 10
A 0.1 M solution of a weak base, B, has a pH of 9.25. Calculate the value of Kb for the base.
A. 1.8 x 10^\( -5 \)
B. 2.0 x 10^\( -5 \)
C. 2.5 x 10^\( -5 \)
D. 3.0 x 10^\( -5 \)
Question 11
A 2.5 g sample of a metal carbonate is heated to produce a metal oxide. If the mass of the metal oxide is 2.0 g, calculate the percentage yield of the metal oxide.
A. 80%
B. 85%
C. 90%
D. 95%
Question 12
The s\tandard enthalpy of formation (ΔH⁰f) of H2(g) is 0 kJ/mol. Calculate the s\tandard enthalpy of combustion (ΔH⁰c) of 1.00 mol of H2(g) u\sing the following equation: 2H2(g) + O2(g) → 2H2O(l).
A. -285.8 kJ/mol
B. -285.8 kJ/mol + 0 kJ/mol
C. -285.8 kJ/mol + 0 kJ/mol
D. -285.8 kJ/mol + 0 kJ/mol
Question 13
A 2.50 L flask contains 0.500 mol of an ideal gas at 298 K. Calculate the pressure of the gas u\sing the ideal gas law, PV = nRT.
A. 1.01 x 10^5 Pa
B. 2.01 x 10^5 Pa
C. 3.01 x 10^5 Pa
D. 4.01 x 10^5 Pa
Question 14
A solution containing 2.0 M $\text{NaOH}$ is mixed with a solution containing 1.0 M $\text{HCl}$. If 50.0 mL of each solution is used, what is the concentration of the resulting solution?
A. 0.5 M
B. 1.0 M
C. 2.0 M
D. 3.0 M
Question 15
A polymer has the following repeating unit: [-CH_2-CH_2-]. Determine the type of polymerization reaction that occurred.
A. Addition polymerization
B. Condensation polymerization
C. Ring-opening polymerization
D. Step-growth polymerization

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