POST UTME CHRISTOPHER UNIVERSITY 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
Determine the molar solubility of Ag2CrO4 in 0.1 M NaCl solution, given that the solubility product cons\tant (Ksp) for Ag2CrO4 is 1.1 × 10^-12.
A. 1.0 × 10^-5 M
B. 1.5 × 10^-5 M
C. 2.0 × 10^-5 M
D. 3.0 × 10^-5 M
Question 2
The reaction between H2 and O2 to form H2O is exothermic. If 10.0 moles of H2 react with oxygen gas to form 20.0 moles of H2O, what is the change in entropy (ΔS) for the reaction?
A. -40 J/K
B. -60 J/K
C. -80 J/K
D. -100 J/K
Question 3
In a reaction between zinc metal and copper(II) sulfate solution, the reaction is represented by the equation: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s). If 2.50 g of zinc metal is added to 100 mL of 0.100 M copper(II) sulfate solution, what is the limiting reac\tant?
A. Zinc metal
B. Copper(II) sulfate solution
C. Zinc sulfate solution
D. Copper metal
Question 4
A 2 L sample of a gas at 300 K and 1 atm is expanded to 5 L at cons\tant temperature. What is the new pressure of the gas?
A. 0.2 atm
B. 0.4 atm
C. 0.6 atm
D. 0.8 atm
Question 5
A 0.500 g sample of a metal is heated in a crucible to produce 0.350 g of the metal. If the metal has a molar mass of 40.0 g/mol, calculate the percentage yield of the metal.
A. 70.0%
B. 75.0%
C. 80.0%
D. 85.0%
Question 6
A 0.1 M solution of a monoprotic acid is titrated with 0.1 M NaOH. If the initial pH of the acid is 2.5, what is the pH after the addition of 20 mL of NaOH?
A. 3.5
B. 4.5
C. 5.5
D. 6.5
Question 7
A solution contains 0.1 M HCl and 0.1 M NaOH. What is the pH of the solution after 25 mL of 0.1 M HCl is added to 25 mL of 0.1 M NaOH?
A. 1
B. 2
C. 3
D. 4
Question 8
Determine the s\tandard enthalpy of formation of CaCO3(s) from the following data: ΔHf(CaO(s)) = -635.09 kJ/mol, ΔHf(CO2(g)) = -393.51 kJ/mol. Assume the reaction is CaO(s) + CO2(g) → CaCO3(s).
A. -1207.6 kJ/mol
B. -1207.6 kJ/mol
C. -1207.6 kJ/mol
D. -1207.6 kJ/mol
Question 9
A 0.5 M solution of NaCl is prepared by dissolving 2.5 g of NaCl in 1 L of water. What is the molarity of the solution?
A. 0.5 M
B. 0.5 M
C. 0.5 M
D. 0.5 M
Question 10
A diagram of a titration setup is shown below. What is the purpose of the burette in the setup?
A. To measure the volume of the solution
B. To measure the pH of the solution
C. To mix the solutions
D. To separate the solutions
Question 11
The electronic configuration of an atom with atomic number 12 is [Xe] 4f^14 5d^10 6s^2 6p^2. What is the atomic number of the element represented by the symbol Xe?
A. 54
B. 56
C. 58
D. 60
Question 12
A 2.00 L sample of a gas at 25°C and 1.00 atm is collected over water at 25°C. If the vapor pressure of water at 25°C is 23.8 torr, what is the partial pressure of the gas?
A. 1.00 atm
B. 0.980 atm
C. 1.02 atm
D. 1.05 atm
Question 13
A 2.50-g sample of a metal (M) is dissolved in 50.0 mL of 0.100 M HCl. The resulting solution is then titrated with 0.0500 M NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the identity of the metal M?
A. Zn
B. Fe
C. Cu
D. Ag
Question 14
A sample of a gas has a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 298 K. What is the volume of the gas at a pressure of 3.0 atm and a temperature of 323 K?
A. 3.2 L
B. 3.2 L
C. 3.2 L
D. 3.2 L
Question 15
A 1.00 L sample of a gas at 27°C and 1.00 atm is collected over water at 25°C. If the vapor pressure of water at 25°C is 23.8 torr, what is the partial pressure of the gas?
A. 1.00 atm
B. 0.980 atm
C. 1.02 atm
D. 1.05 atm

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