POST UTME UNIOSUN 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The s\tandard electrode potential (E°) of the Zn^2+/Zn couple is -0.76 V. What is the s\tandard electrode potential (E°) of the Cu^2+/Cu couple if the s\tandard electrode potential (E°) of the Cu^2+/Cu couple is 0.34 V?
A. -0.42 V
B. -0.76 V
C. 0.34 V
D. 0.76 V
Question 2
A 10 mL sample of a 0.1 M solution of NaOH is titrated with a 0.1 M solution of HCl. Calculate the pH of the solution after the titration.
A. 1
B. 2
C. 3
D. 4
Question 3
A 2.00 g sample of an unknown nonmetal is burned in a bomb calorimeter. If the heat of combustion is 35.0 kJ/g, what is the molar mass of the nonmetal?
A. 40.0 g/mol
B. 50.0 g/mol
C. 60.0 g/mol
D. 70.0 g/mol
Question 4
A 10 mL sample of a 0.1 M solution of NaOH is titrated with a 0.1 M solution of HCl. Calculate the pH of the solution after the titration.
A. 1
B. 2
C. 3
D. 4
Question 5
A 2.00 g sample of an unknown hydrocarbon is burned in a bomb calorimeter. If the heat of combustion is 42.0 kJ/g, what is the molar mass of the hydrocarbon?
A. 50.0 g/mol
B. 60.0 g/mol
C. 70.0 g/mol
D. 80.0 g/mol
Question 6
A 0.1 M solution of a weak acid, HA, is titrated with 0.1 M NaOH. The initial pH of the acid solution is 3.5. If 20 mL of NaOH is added, the pH of the solution is 4.5. What is the value of the dissociation cons\tant (Ka) of the acid?
A. 1.0 x 10^\( -4 \)
B. 1.0 x 10^\( -5 \)
C. 1.0 x 10^\( -6 \)
D. 1.0 x 10^\( -7 \)
Question 7
A solution containing 0.250 mol of NaCl is diluted to a total volume of 1.50 L. Calculate the resulting concentration of NaCl.
A. 0.167 M
B. 0.167 M
C. 0.250 M
D. 0.500 M
Question 8
At 25°C, 1.00 L of an ideal gas at 3.00 atm is compressed to 0.500 L. What is the new pressure in atm?
A. 1.50 atm
B. 2.25 atm
C. 3.00 atm
D. 4.50 atm
Question 9
The reaction of a hydrocarbon, C6H14, with oxygen gas (O2) in the presence of a catalyst produces carbon dioxide and water. What is the balanced equation for the reaction?
A. C6H14 + 9O2 → 6CO2 + 7H2O
B. C6H14 + 8O2 → 6CO2 + 6H2O
C. C6H14 + 7O2 → 6CO2 + 5H2O
D. C6H14 + 6O2 → 6CO2 + 4H2O
Question 10
Determine the type of hybridization exhibited by the central atom in the molecule CH2Cl2.
A. sp3
B. sp2
C. sp
D. dsp3
Question 11
A 10.0 g sample of a metal is heated in a crucible until it melts. The mass of the crucible and metal is 10.5 g. The mass of the crucible alone is 5.00 g. What is the mass of the metal?
A. 5.00 g
B. 7.50 g
C. 10.0 g
D. 12.5 g
Question 12
A 2.0 g sample of a polymer is dissolved in 100 mL of a solvent. What is the concentration \( in g/mL \) of the polymer solution?
A. 0.02 g/mL
B. 0.04 g/mL
C. 0.06 g/mL
D. 0.08 g/mL
Question 13
A 2.5 g sample of a polymer is dissolved in 100 mL of a solvent. Calculate the molar mass of the polymer if the osmotic pressure of the solution is 2.5 atm at 25°C.
A. 1000 g/mol
B. 2000 g/mol
C. 3000 g/mol
D. 4000 g/mol
Question 14
The reaction of 2.00 g of an unknown hydrocarbon with 50.0 mL of 1.00 M HCl produces 1.00 g of CO2 and 1.00 g of H2O. What is the empirical formula of the hydrocarbon?
A. C2H4
B. C3H6
C. C4H8
D. C5H10
Question 15
A sample of a gas is collected over water at a temperature of 25°C and a pressure of 1 atm. If the volume of the gas is 2.5 L and the vapor pressure of water at 25°C is 0.0313 atm, what is the partial pressure of the gas?
A. 0.9687 atm
B. 0.9697 atm
C. 0.9707 atm
D. 0.9717 atm

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